[inspector] run microtasks after async Runtime.evaluate

If promise was resolved before adding handler in Runtime.evaluate method then this callback won't be called. We need to run microtasks after adding handlers.

R=dgozman@chromium.org,alph@chromium.org

Review-Url: https://codereview.chromium.org/2371773004
Cr-Commit-Position: refs/heads/master@{#39793}

src/inspector/v8-runtime-agent-impl.cc

@@ -78,6 +78,8 @@ class ProtocolPromiseHandler {
       callback->sendFailure(notPromiseError);
       return;
     }
+    v8::MicrotasksScope microtasks_scope(inspector->isolate(),
+                                         v8::MicrotasksScope::kRunMicrotasks);
     v8::Local<v8::Promise> promise =
         v8::Local<v8::Promise>::Cast(value.ToLocalChecked());
     Callback* rawCallback = callback.get();