Show stack traces in console for unhandled promise rejection messages.

LayoutTests/http/tests/inspector/console-test.js

Index: LayoutTests/http/tests/inspector/console-test.js
diff --git a/LayoutTests/http/tests/inspector/console-test.js b/LayoutTests/http/tests/inspector/console-test.js
index e5f53432bf6c86cc81e6d1d66cb865b504d414a7..4c27b3f4d5a2e8b4cfc41b0faf33d157bb4fe31b 100644
--- a/LayoutTests/http/tests/inspector/console-test.js
+++ b/LayoutTests/http/tests/inspector/console-test.js
@@ -72,6 +72,12 @@ InspectorTest.fixConsoleViewportDimensions = function(width, height)
     viewport.invalidate();
 }
 
+InspectorTest.consoleMessagesCount = function()
+{
+    var consoleView = WebInspector.ConsolePanel._view();
+    return consoleView._consoleMessages.length;
+}
+
 InspectorTest.dumpConsoleMessages = function(printOriginatingCommand, dumpClassNames, formatter)
 {
     InspectorTest.addResults(InspectorTest.dumpConsoleMessagesIntoArray(printOriginatingCommand, dumpClassNames, formatter));