Fix "report the exception" in Custom Elements V1

third_party/WebKit/Source/bindings/core/v8/ScriptCustomElementDefinition.cpp

Index: third_party/WebKit/Source/bindings/core/v8/ScriptCustomElementDefinition.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/ScriptCustomElementDefinition.cpp b/third_party/WebKit/Source/bindings/core/v8/ScriptCustomElementDefinition.cpp
index 6c7b1e3de4e39b0513efb14349dddf12a81ff0b4..77161073a5eae4edfa6169df18935a0db2b1e633 100644
--- a/third_party/WebKit/Source/bindings/core/v8/ScriptCustomElementDefinition.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/ScriptCustomElementDefinition.cpp
@@ -189,6 +189,20 @@ HTMLElement* ScriptCustomElementDefinition::createElementSync(
     return toHTMLElement(element);
 }
 
+static void dispatchErrorEvent(ExceptionState& exceptionState)
+{
+    // Report an exception
+    // https://html.spec.whatwg.org/multipage/webappapis.html#report-the-exception
+    DCHECK(exceptionState.hadException());
+    v8::TryCatch tryCatch(exceptionState.isolate());
+    tryCatch.SetVerbose(true);
+    exceptionState.throwIfNeeded();
+    tryCatch.ReThrow();

[Yuki, 2016/08/19 07:31:33]

This usage is simply wrong.

+
+    // Clear the ExceptionState since it's handled.
+    exceptionState.clearException();
+}
+
 HTMLElement* ScriptCustomElementDefinition::createElementSync(
     Document& document, const QualifiedName& tagName)
 {
@@ -202,16 +216,13 @@ HTMLElement* ScriptCustomElementDefinition::createElementSync(
         "CustomElement", constructor(), isolate);
     HTMLElement* element = createElementSync(document, tagName, exceptionState);
 
-    if (exceptionState.hadException() || !element) {
+    if (exceptionState.hadException()) {
+        DCHECK(!element);
         // 7. If this step throws an exception, then report the exception, ...
-        {
-            v8::TryCatch tryCatch(isolate);
-            tryCatch.SetVerbose(true);
-            exceptionState.throwIfNeeded();
-        }
-
+        dispatchErrorEvent(exceptionState);
         return CustomElement::createFailedElement(document, tagName);
     }
+    DCHECK(element);
     return element;
 }