DevTools: Fix flaky console-uncaught-promise.html test.

TBR=loislo

Review URL: https://codereview.chromium.org/670523002

git-svn-id: svn://svn.chromium.org/blink/trunk@184009 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/LayoutTests/inspector/console/console-uncaught-promise-expected.txt

@@ -18,12 +18,12 @@ console-uncaught-promise.html:1 Unhandled promise rejection Promise
         [[PromiseStatus]]: "rejected"
         [[PromiseValue]]: Error: inspector.err1
         console-uncaught-promise.html:9 runPromises
-        console-uncaught-promise.html:40 timeout
+        console-uncaught-promise.html:47 timeout
 
     console-uncaught-promise.html:27 Unhandled promise rejection Promise {[[PromiseStatus]]: "rejected", [[PromiseValue]]: Error: inspector.err2}
         __proto__: Promise
         [[PromiseStatus]]: "rejected"
         [[PromiseValue]]: Error: inspector.err2
         console-uncaught-promise.html:27 runPromises
-        console-uncaught-promise.html:40 timeout
+        console-uncaught-promise.html:47 timeout
 

third_party/WebKit/LayoutTests/inspector/console/console-uncaught-promise.html

@@ -30,7 +30,14 @@ function runPromises(source)
 function onload()
 {
     runPromises("onload");
-    runTest();
+
+    if (window.testRunner) {
+        testRunner.dumpAsText();
+        testRunner.waitUntilDone();
+    }
+
+    // Run tests after all microtasks.
+    setTimeout(runTest, 0);
 }
 
 function runPromisesFromInspector()