[bindings] Break V8Binding::toDouble into fast inline and slower non-inline code paths.

Source/bindings/core/v8/V8Binding.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Google Inc. 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
@@ skipping 513 matching lines @@
     float numberValue = toFloat(value, exceptionState);
     if (exceptionState.hadException())
         return 0;
     if (!std::isfinite(numberValue)) {
         exceptionState.throwTypeError("The provided float value is non-finite.");
         return 0;
     }
     return numberValue;
 }
 
-double toDouble(v8::Handle<v8::Value> value, ExceptionState& exceptionState)
+double toDoubleSlow(v8::Handle<v8::Value> value, ExceptionState& exceptionState)
 {
-    if (value->IsNumber())
-        return value->NumberValue();
-
     v8::Isolate* isolate = v8::Isolate::GetCurrent();
     v8::TryCatch block(isolate);
-    v8::Local<v8::Number> numberObject(value->ToNumber(isolate));
+    double doubleValue = value->NumberValue();
     if (block.HasCaught()) {
         exceptionState.rethrowV8Exception(block.Exception());
         return 0;
     }
-    return numberObject->NumberValue();
+    return doubleValue;
 }
 
 double toRestrictedDouble(v8::Handle<v8::Value> value, ExceptionState& exceptionState)
 {
     double numberValue = toDouble(value, exceptionState);
     if (exceptionState.hadException())
         return 0;
     if (!std::isfinite(numberValue)) {
         exceptionState.throwTypeError("The provided double value is non-finite.");
         return 0;
@@ skipping 493 matching lines @@
     return m_resourceName;
 }
 
 PassRefPtr<TraceEvent::ConvertableToTraceFormat> devToolsTraceEventData(v8::Isolate* isolate, ExecutionContext* context, v8::Handle<v8::Function> function)
 {
     DevToolsFunctionInfo info(function);
     return InspectorFunctionCallEvent::data(context, info.scriptId(), info.resourceName(), info.lineNumber());
 }
 
 } // namespace blink