[inspector] extend protocol for code coverage.

src/inspector/js_protocol.json

 {
     "version": { "major": "1", "minor": "2" },
     "domains": [
     {
         "domain": "Schema",
         "description": "Provides information about the protocol schema.",
         "types": [
             {
                 "id": "Domain",
                 "type": "object",
@@ skipping 186 matching lines @@
             {
                 "id": "StackTrace",
                 "type": "object",
                 "description": "Call frames for assertions or error messages.",
                 "properties": [
                     { "name": "description", "type": "string", "optional": true, "description": "String label of this stack trace. For async traces this may be a name of the function that initiated the async call." },
                     { "name": "callFrames", "type": "array", "items": { "$ref": "CallFrame" }, "description": "JavaScript function name." },
                     { "name": "parent", "$ref": "StackTrace", "optional": true, "description": "Asynchronous JavaScript stack trace that preceded this stack, if available." },
                     { "name": "promiseCreationFrame", "$ref": "CallFrame", "optional": true, "experimental": true, "description": "Creation frame of the Promise which produced the next synchronous trace when resolved, if available." }
                 ]
+            },
+            {   "id": "CoverageRange",
+                "type": "object",
+                "description": "Coverage data for a source range.",
+                "properties": [
+                    { "name": "startLineNumber", "type": "integer", "description": "JavaScript script line number (0-based) for the range start." },
+                    { "name": "startColumnNumber", "type": "integer", "description": "JavaScript script column number (0-based) for the range start." },
+                    { "name": "endLineNumber", "type": "integer", "description": "JavaScript script line number (0-based) for the range end." },
+                    { "name": "endColumnNumber", "type": "integer", "description": "JavaScript script column number (0-based) for the range end." },
+                    { "name": "count", "type": "integer", "description": "Collected execution count of the source range." }
+                ],
+                "experimental": "true"
+            },
+            {   "id": "FunctionCoverage",
+                "type": "object",
+                "description": "Coverage data for a JavaScript function.",
+                "properties": [
+                    { "name": "functionName", "type": "string", "description": "JavaScript function name." },
+                    { "name": "ranges", "type": "array", "items": { "$ref": "CoverageRange" }, "description": "Source ranges inside the function with coverage data." }
+                ],
+                "experimental": "true"
+            },
+            {
+                "id": "ScriptCoverage",
+                "type": "object",
+                "description": "Coverage data for a JavaScript script.",
+                "properties": [
+                    { "name": "scriptId", "$ref": "ScriptId", "description": "JavaScript script id." },
+                    { "name": "url", "type": "string", "description": "JavaScript script name or url." },
+                    { "name": "functions", "type": "array", "items": { "$ref": "FunctionCoverage" }, "description": "Functions contained in the script that has coverage data." }
+                ],
+                "experimental": "true"
             }
         ],
         "commands": [
             {
                 "name": "evaluate",
                 "parameters": [
                     { "name": "expression", "type": "string", "description": "Expression to evaluate." },
                     { "name": "objectGroup", "type": "string", "optional": true, "description": "Symbolic group name that can be used to release multiple objects." },
                     { "name": "includeCommandLineAPI", "type": "boolean", "optional": true, "description": "Determines whether Command Line API should be available during the evaluation." },
                     { "name": "silent", "type": "boolean", "optional": true, "description": "In silent mode exceptions thrown during evaluation are not reported and do not pause execution. Overrides <code>setPauseOnException</code> state." },
@@ skipping 119 matching lines @@
                     { "name": "includeCommandLineAPI", "type": "boolean", "optional": true, "description": "Determines whether Command Line API should be available during the evaluation." },
                     { "name": "returnByValue", "type": "boolean", "optional": true, "description": "Whether the result is expected to be a JSON object which should be sent by value." },
                     { "name": "generatePreview", "type": "boolean", "optional": true, "description": "Whether preview should be generated for the result." },
                     { "name": "awaitPromise", "type": "boolean", "optional": true, "description": "Whether execution should wait for promise to be resolved. If the result of evaluation is not a Promise, it's considered to be an error." }
                 ],
                 "returns": [
                     { "name": "result", "$ref": "RemoteObject", "description": "Run result." },
                     { "name": "exceptionDetails", "$ref": "ExceptionDetails", "optional": true, "description": "Exception details."}
                 ],
                 "description": "Runs script with given id in a given context."
+            },
+            {
+                "name": "startPreciseCoverage",
+                "description": "Enable precise code coverage. Coverage data for JavaScript executed before enabling precise code coverage may be incomplete. Enabling prevents running optimized code and resets execution counters.",
+                "experimental": true
+            },
+            {
+                "name": "stopPreciseCoverage",
+                "description": "Disable precise code coverage. Disabling releases unnecessary execution count records and allows executing optimized code.",
+                "experimental": true
+            },
+            {
+                "name": "takePreciseCoverage",
+                "returns": [
+                    { "name": "result", "type": "array", "items": { "$ref": "ScriptCoverage" }, "description": "Coverage data for the current isolate." }
+                ],
+                "description": "Collect coverage data for the current isolate, and resets execution counters. Precise code coverage needs to have started.",
+                "experimental": true
+            },
+            {
+                "name": "getBestEffortCoverage",
+                "returns": [
+                    { "name": "result", "type": "array", "items": { "$ref": "ScriptCoverage" }, "description": "Coverage data for the current isolate." }
+                ],
+                "description": "Collect coverage data for the current isolate. The coverage data may be incomplete due to garbage collection.",
+                "experimental": true
             }
         ],
         "events": [
             {
                 "name": "executionContextCreated",
                 "parameters": [
                     { "name": "context", "$ref": "ExecutionContextDescription", "description": "A newly created execution contex." }
                 ],
                 "description": "Issued when new execution context is created."
             },
@@ skipping 640 matching lines @@
             {
                 "name": "heapStatsUpdate",
                 "description": "If heap objects tracking has been started then backend may send update for one or more fragments",
                 "parameters": [
                     { "name": "statsUpdate", "type": "array", "items": { "type": "integer" }, "description": "An array of triplets. Each triplet describes a fragment. The first integer is the fragment index, the second integer is a total count of objects for the fragment, the third integer is a total size of the objects for the fragment."}
                 ]
             }
         ]
     }]
 }