[inspector] extend protocol for code coverage.

test/mjsunit/code-coverage-precise.js

 // Copyright 2017 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --allow-natives-syntax --no-always-opt
 
 // Test precise code coverage.
 
 function GetCoverage(source) {
   for (var script of %DebugCollectCoverage()) {
-    if (script.script.source == source) return script.toplevel;
+    if (script.script.source == source) return script;
   }
   return undefined;
 }
 
-function ApplyCoverageToSource(source, range) {
-  var content = "";
-  var cursor = range.start;
-  if (range.inner) for (var inner of range.inner) {
-    content += source.substring(cursor, inner.start);
-    content += ApplyCoverageToSource(source, inner);
-    cursor = inner.end;
-  }
-  content += source.substring(cursor, range.end);
-  return `[${content}](${range.name}:${range.count})`;
-}
-
 function TestCoverage(name, source, expectation) {
   source = source.trim();
   eval(source);
-  %CollectGarbage("remove dead objects");
+  %CollectGarbage("collect dead objects");
   var coverage = GetCoverage(source);
-  if (expectation === undefined) {
-    assertEquals(undefined, coverage);
-  } else {
-    expectation = expectation.trim();
-    var result = ApplyCoverageToSource(source, coverage);
-    print(result);
-    assertEquals(expectation, result, name + " failed");
-  }
+  var result = JSON.stringify(coverage);
+  print(result);
+  assertEquals(JSON.stringify(expectation), result, name + " failed");
 }
 
-
 // Without precise coverage enabled, we lose coverage data to the GC.
 TestCoverage(
 "call an IIFE",
 `
 (function f() {})();
 `,
 undefined  // The IIFE has been garbage-collected.
 );
 
 TestCoverage(
 "call locally allocated function",
 `
 for (var i = 0; i < 10; i++) {
   let f = () => 1;
   i += f();
 }
 `,
 undefined
 );
 
 // This does not happen with precise coverage enabled.
 %DebugTogglePreciseCoverage(true);
 
 TestCoverage(
 "call an IIFE",
 `
 (function f() {})();
 `,
-`
-[([function f() {}](f:1))();](:1)
-`
+[{"start":0,"end":20,"count":1},{"start":1,"end":16,"count":1}]
 );
 
 TestCoverage(
 "call locally allocated function",
 `
 for (var i = 0; i < 10; i++) {
   let f = () => 1;
   i += f();
 }
 `,
-`
-[for (var i = 0; i < 10; i++) {
-  let f = [() => 1](f:5);
-  i += f();
-}](:1)
-`
+[{"start":0,"end":63,"count":1},{"start":41,"end":48,"count":5}]
 );
 
 %DebugTogglePreciseCoverage(false);