Get rid of last uses of deprecated toWebCoreString(v8::Handle<v8::Value>)

Source/bindings/v8/custom/V8OscillatorNodeCustom.cpp

Index: Source/bindings/v8/custom/V8OscillatorNodeCustom.cpp
diff --git a/Source/bindings/v8/custom/V8OscillatorNodeCustom.cpp b/Source/bindings/v8/custom/V8OscillatorNodeCustom.cpp
index e7c49da7c7209e0f4dcabb20b161e6bf91e925f9..80bf07a18cdf9d11a34f769fbb236f728f377c4c 100644
--- a/Source/bindings/v8/custom/V8OscillatorNodeCustom.cpp
+++ b/Source/bindings/v8/custom/V8OscillatorNodeCustom.cpp
@@ -45,7 +45,7 @@ void V8OscillatorNode::typeAttributeSetterCustom(v8::Local<v8::Value> value, con
     }
 
     if (value->IsString()) {
-        String type = toWebCoreString(value);
+        String type = toWebCoreString(value.As<v8::String>());
         if (type == "sine" || type == "square" || type == "sawtooth" || type == "triangle") {
             imp->setType(type);
             return;