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

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 ae76dca6218a539d32c75224a033ead250f7cadc..54eb709dfd0ed28de7083e9d7f9b7e25b5599d18 100644
--- a/Source/bindings/core/v8/V8Binding.cpp
+++ b/Source/bindings/core/v8/V8Binding.cpp
@@ -482,12 +482,21 @@ uint64_t toUInt64(v8::Handle<v8::Value> value)
 
 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();
 }