IntersectionObserver: make exceptions match spec

third_party/WebKit/Source/bindings/core/v8/custom/V8IntersectionObserverCustom.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "bindings/core/v8/V8IntersectionObserver.h"
 
 #include "bindings/core/v8/ExceptionMessages.h"
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/V8Binding.h"
 #include "bindings/core/v8/V8DOMWrapper.h"
@@ skipping 18 matching lines @@
     }
 
     if (info.Length() > 1 && !isUndefinedOrNull(info[1]) && !info[1]->IsObject()) {
         V8ThrowException::throwTypeError(info.GetIsolate(), ExceptionMessages::failedToExecute("createIntersectionObserver", "Intersection", "IntersectionObserverInit (parameter 2) is not an object."));
         return;
     }
 
     IntersectionObserverInit intersectionObserverInit;
     ExceptionState exceptionState(ExceptionState::ConstructionContext, "Intersection", info.Holder(), info.GetIsolate());
     V8IntersectionObserverInit::toImpl(info.GetIsolate(), info[1], intersectionObserverInit, exceptionState);
-    if (exceptionState.hadException()) {
-        V8ThrowException::throwGeneralError(info.GetIsolate(), exceptionState.message());
+    if (exceptionState.throwIfNeeded())
+        return;
+
+    IntersectionObserverCallback* callback = new V8IntersectionObserverCallback(v8::Local<v8::Function>::Cast(info[0]), wrapper, ScriptState::current(info.GetIsolate()));
+    IntersectionObserver* observer = IntersectionObserver::create(intersectionObserverInit, *callback, exceptionState);
+    if (exceptionState.throwIfNeeded())
+        return;
+    if (!observer) {

[haraken, 2016/02/29 23:35:56]

Can this be ASSERT(observer)? If observer is null, an exception should have been
thrown at line 44.

[szager1, 2016/02/29 23:45:39]

Done.

+        V8ThrowException::throwGeneralError(info.GetIsolate(), "Unknown error while constructing IntersectionObserver.");
         return;
     }
 
-    IntersectionObserverCallback* callback = new V8IntersectionObserverCallback(v8::Local<v8::Function>::Cast(info[0]), wrapper, ScriptState::current(info.GetIsolate()));
-    IntersectionObserver* observer = IntersectionObserver::create(intersectionObserverInit, *callback, exceptionState);
-    if (!observer || exceptionState.hadException()) {
-        V8ThrowException::throwGeneralError(info.GetIsolate(), exceptionState.message());
-        return;
-    }
-
     v8SetReturnValue(info, V8DOMWrapper::associateObjectWithWrapper(info.GetIsolate(), observer, &wrapperTypeInfo, wrapper));
 }
 
 void V8IntersectionObserver::visitDOMWrapper(v8::Isolate* isolate, ScriptWrappable* scriptWrappable, const v8::Persistent<v8::Object>& wrapper)
 {
     IntersectionObserver* observer = scriptWrappable->toImpl<IntersectionObserver>();
     for (auto& observation : observer->observations()) {
         Element* target = observation->target();
         if (!target)
             continue;
         v8::UniqueId id(reinterpret_cast<intptr_t>(V8GCController::opaqueRootForGC(isolate, target)));
         isolate->SetReferenceFromGroup(id, wrapper);
     }
 }
 
 } // namespace blink