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

Source/bindings/core/v8/V8Binding.cpp

Index: Source/bindings/core/v8/V8Binding.cpp
diff --git a/Source/bindings/core/v8/V8Binding.cpp b/Source/bindings/core/v8/V8Binding.cpp
index 99d6c4facf7b935226d51d804287b84e0b28dcc4..3496cecf602a09291cef3c2df2a8cbaa960414ca 100644
--- a/Source/bindings/core/v8/V8Binding.cpp
+++ b/Source/bindings/core/v8/V8Binding.cpp
@@ -531,19 +531,16 @@ float toRestrictedFloat(v8::Handle<v8::Value> value, ExceptionState& exceptionSt
     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)