Implement platform deleters per spec.

Source/bindings/tests/results/V8TestEventTarget.cpp

Index: Source/bindings/tests/results/V8TestEventTarget.cpp
diff --git a/Source/bindings/tests/results/V8TestEventTarget.cpp b/Source/bindings/tests/results/V8TestEventTarget.cpp
index 315c861ef91db82d8a53160430a55a070f185d77..4b986581d50fdda7dc25b1032a3723de6c4c2f70 100644
--- a/Source/bindings/tests/results/V8TestEventTarget.cpp
+++ b/Source/bindings/tests/results/V8TestEventTarget.cpp
@@ -145,10 +145,11 @@ static void indexedPropertyDeleter(unsigned index, const v8::PropertyCallbackInf
 {
     TestEventTarget* collection = V8TestEventTarget::toNative(info.Holder());
     ExceptionState exceptionState(info.Holder(), info.GetIsolate());
-    bool result = collection->anonymousIndexedDeleter(index, exceptionState);
+    DeleteResult result = collection->anonymousIndexedDeleter(index, exceptionState);
     if (exceptionState.throwIfNeeded())
         return;
-    return v8SetReturnValueBool(info, result);
+    if (result != DeleteUnknownProperty)
+        return v8SetReturnValueBool(info, result == DeleteSuccess);
 }
 
 static void indexedPropertyDeleterCallback(uint32_t index, const v8::PropertyCallbackInfo<v8::Boolean>& info)
@@ -215,8 +216,9 @@ static void namedPropertyDeleter(v8::Local<v8::String> name, const v8::PropertyC
 {
     TestEventTarget* collection = V8TestEventTarget::toNative(info.Holder());
     AtomicString propertyName = toCoreAtomicString(name);
-    bool result = collection->anonymousNamedDeleter(propertyName);
-    return v8SetReturnValueBool(info, result);
+    DeleteResult result = collection->anonymousNamedDeleter(propertyName);
+    if (result != DeleteUnknownProperty)
+        return v8SetReturnValueBool(info, result == DeleteSuccess);
 }
 
 static void namedPropertyDeleterCallback(v8::Local<v8::String> name, const v8::PropertyCallbackInfo<v8::Boolean>& info)