This patch teaches Page.waitForNavigation to correctly handle navigation
to pages that have frames that might never load.
These frames include:
- frames which main resource loading was aborted due to mixed-content
error
- frames that artificially called `window.stop()` to interrupt loading
themselves
Fixes#1936.
This patch implements FrameManager which is responsible for maintaining
the frame tree. FrameManager is quite basic: it sends FrameAttached,
FrameDetached and FrameNavigated events, and can report mainFrame and
all frames.
The next step would be moving certain Page API's to the Frame. For
example, such method as Page.evaluate, Page.navigate and others should
be available on Frame object as well.
References #4