Remove grab-bag includes of v8.h from everywhere.

test/cctest/trace-extension.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 15 matching lines @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #ifndef V8_TEST_CCTEST_TRACE_EXTENSION_H_
 #define V8_TEST_CCTEST_TRACE_EXTENSION_H_
 
 #include "src/v8.h"
 
 namespace v8 {
 namespace internal {
 
+struct TickSample;
+
 class TraceExtension : public v8::Extension {
  public:
   TraceExtension() : v8::Extension("v8/trace", kSource) { }
   virtual v8::Handle<v8::FunctionTemplate> GetNativeFunctionTemplate(
       v8::Isolate* isolate,
       v8::Handle<v8::String> name);
   static void Trace(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void JSTrace(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void JSEntrySP(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void JSEntrySPLevel2(const v8::FunctionCallbackInfo<v8::Value>& args);
   static Address GetJsEntrySp();
   static void InitTraceEnv(TickSample* sample);
   static void DoTrace(Address fp);
  private:
   static Address GetFP(const v8::FunctionCallbackInfo<v8::Value>& args);
   static const char* kSource;
 };
 
 } }  // namespace v8::internal
 
 #endif