Doc: update QML Profiler information

The JavaScript events are integrated into the Timeline and Events
views for apps that use the V4 engine and are built with Qt 5.3.
Updated the Events view screenshot and removed the JavaScript
view screenshot.

Change-Id: Id7e74d91343ff049df580d487e729fdb20c57b0e
Reviewed-by: Ulf Hermann <ulf.hermann@digia.com>
QmlDesigner: Always warn asynchronously in exceptions

Exceptions are likely to be triggered from QML code.
Calling QMessageBox::warning() results in a call to exec() and
exec() returns back into the Qt event loop.

This is dangerous, because QML might have scheduled a deleteLater
which is then executed by exec(). This can crash the application, because
the object is supposed to be "deleted later" and not directly
as a side effect of the signal that was emmited by QML.

Task-number: QTCREATORBUG-11946

Change-Id: Icb884847633bd421d3dc7bc034d598ef84d39429
Reviewed-by: Marco Bubke <marco.bubke@digia.com>