bindings: Throw a type error if converting an interface or callback function fails.

third_party/WebKit/Source/bindings/tests/results/core/V8TestCallbackFunctions.cpp

Index: third_party/WebKit/Source/bindings/tests/results/core/V8TestCallbackFunctions.cpp
diff --git a/third_party/WebKit/Source/bindings/tests/results/core/V8TestCallbackFunctions.cpp b/third_party/WebKit/Source/bindings/tests/results/core/V8TestCallbackFunctions.cpp
index f83f34605f58f7dd9b9ba1f4f39f88c32025e561..6a547f2296eb2bfaa81e763d8125de19adf496b9 100644
--- a/third_party/WebKit/Source/bindings/tests/results/core/V8TestCallbackFunctions.cpp
+++ b/third_party/WebKit/Source/bindings/tests/results/core/V8TestCallbackFunctions.cpp
@@ -335,7 +335,10 @@ TestCallbackFunctions* V8TestCallbackFunctions::toImplWithTypeCheck(v8::Isolate*
 }
 
 TestCallbackFunctions* NativeValueTraits<TestCallbackFunctions>::nativeValue(v8::Isolate* isolate, v8::Local<v8::Value> value, ExceptionState& exceptionState) {
-  return V8TestCallbackFunctions::toImplWithTypeCheck(isolate, value);
+  TestCallbackFunctions* nativeValue = V8TestCallbackFunctions::toImplWithTypeCheck(isolate, value);
+  if (!nativeValue)
+    exceptionState.throwTypeError("Unable to convert value to TestCallbackFunctions.");
+  return nativeValue;
 }
 
 }  // namespace blink