Revert "Simplify and fix implicit closure check, speed up Closure_equals"

runtime/vm/kernel_binary_flowgraph.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/kernel_binary_flowgraph.h"
 
 #include "vm/compiler.h"
 #include "vm/longjump.h"
 #include "vm/object_store.h"
 
@@ skipping 113 matching lines @@
   parsed_function->SetNodeSequence(
       new SequenceNode(TokenPosition::kNoSource, scope_));
 
   intptr_t parent_offset = -1;
   builder_->SetOffset(kernel_offset_);
 
   FunctionNodeHelper function_node_helper(builder_);
 
   switch (function.kind()) {
     case RawFunction::kClosureFunction:
-    case RawFunction::kImplicitClosureFunction:
     case RawFunction::kConvertedClosureFunction:
     case RawFunction::kRegularFunction:
     case RawFunction::kGetterFunction:
     case RawFunction::kSetterFunction:
     case RawFunction::kConstructor: {
       const Tag tag = builder_->PeekTag();
       parent_offset = builder_->ReadUntilFunctionNode();
       function_node_helper.ReadUntilExcluding(
           FunctionNodeHelper::kPositionalParameters);
       current_function_async_marker_ = function_node_helper.async_marker_;
@@ skipping 3271 matching lines @@
   // will not need an AST.  The code generator will assume that there is a
   // local variable stack slot allocated for the current context and (I
   // think) that the runtime will expect it to be at a fixed offset which
   // requires allocating an unused expression temporary variable.
   set_scopes(parsed_function()->EnsureKernelScopes());
 
   SetOffset(kernel_offset);
 
   switch (function.kind()) {
     case RawFunction::kClosureFunction:
-    case RawFunction::kImplicitClosureFunction:
     case RawFunction::kConvertedClosureFunction:
     case RawFunction::kRegularFunction:
     case RawFunction::kGetterFunction:
     case RawFunction::kSetterFunction: {
       ReadUntilFunctionNode();  // read until function node.
       if (function.IsImplicitClosureFunction()) {
         return BuildGraphOfImplicitClosureFunction(function);
       } else if (function.IsConvertedClosureFunction()) {
         return BuildGraphOfConvertedClosureFunction(function);
       }
@@ skipping 3832 matching lines @@
     }
   }
 
   return Array::Handle(Array::null());
 }
 
 }  // namespace kernel
 }  // namespace dart
 
 #endif  // !defined(DART_PRECOMPILED_RUNTIME)