Add toDouble() helper, and use toFloat()/toDouble() for conversions

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 464 matching lines @@
 }
 
 uint64_t toUInt64(v8::Handle<v8::Value> value)
 {
     NonThrowableExceptionState exceptionState;
     return toUInt64(value, NormalConversion, exceptionState);
 }
 
 float toFloat(v8::Handle<v8::Value> value, ExceptionState& exceptionState)
 {
+    return static_cast<float>(toDouble(value, exceptionState));
+}
+
+double toDouble(v8::Handle<v8::Value> value, ExceptionState& exceptionState)
+{
+    if (value->IsNumber())
+        return value->NumberValue();
+
     v8::TryCatch block;
     v8::Local<v8::Number> numberObject(value->ToNumber());
     if (block.HasCaught()) {
         exceptionState.rethrowV8Exception(block.Exception());
         return 0;
     }
+
     return numberObject->NumberValue();
 }
 
 String toByteString(v8::Handle<v8::Value> value, ExceptionState& exceptionState)
 {
     // Handle null default value.
     if (value.IsEmpty())
         return String();
 
     // From the Web IDL spec: http://heycam.github.io/webidl/#es-ByteString
@@ skipping 452 matching lines @@
 
 v8::Local<v8::Value> v8IteratorResult(v8::Isolate* isolate, v8::Handle<v8::Value> value)
 {
     v8::Local<v8::Object> result = v8::Object::New(isolate);
     result->Set(v8String(isolate, "value"), value);
     result->Set(v8String(isolate, "done"), v8Boolean(false, isolate));
     return result;
 }
 
 } // namespace blink