[inspector] fix use-after-free in ConsoleHelper::reportCall

InspectedContext can be destroyed inside of V8ConsoleMessage::createForConsoleAPI call.

BUG=chromium:646175
R=dgozman@chromium.org,alph@chromium.org

Review-Url: https://codereview.chromium.org/2388463002
Cr-Commit-Position: refs/heads/master@{#39939}

src/inspector/v8-console.cc

@@ -93,12 +93,13 @@ class ConsoleHelper {
                   const std::vector<v8::Local<v8::Value>>& arguments) {
     InspectedContext* inspectedContext = ensureInspectedContext();
     if (!inspectedContext) return;
+    int contextGroupId = inspectedContext->contextGroupId();
     V8InspectorImpl* inspector = inspectedContext->inspector();
     std::unique_ptr<V8ConsoleMessage> message =
         V8ConsoleMessage::createForConsoleAPI(
             inspector->client()->currentTimeMS(), type, arguments,
             inspector->debugger()->captureStackTrace(false), inspectedContext);
-    inspector->ensureConsoleMessageStorage(inspectedContext->contextGroupId())
+    inspector->ensureConsoleMessageStorage(contextGroupId)
         ->addMessage(std::move(message));
   }