Fix resource leak in run-bindings-tests

I messed up usage of @contextlib.contextmanager in r-b-t:
it *does* need a try...finally clause,
so r-b-t leaks resources if there's an exception
(better than before, when it leaked even without exceptions,
but still fails sometimes).

Stefan Haller pointed this out in a comment:
https://codereview.chromium.org/228323002/#msg3
(thanks Stefan!)

...so I'm fixing this here.

This is sufficiently tricky that I've documented it (in my free time)
at Wikibooks and StackOverflow:
http://en.wikibooks.org/wiki/Python_Programming/Context_Managers
http://stackoverflow.com/questions/6884991/how-to-delete-dir-created-by-python-tempfile-mkdtemp/22726782#22726782

TBR=haraken
BUG=341748
NOTRY=true

Review URL: https://codereview.chromium.org/234553002

git-svn-id: svn://svn.chromium.org/blink/trunk@171342 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Add "Save All" shortcut to the sources editor.

It is Cmd+Option+S on Mac (sublime text default) and Ctrl+Shift+S on other platforms.

BUG=356601
R=lushnikov

Review URL: https://codereview.chromium.org/235053003

git-svn-id: svn://svn.chromium.org/blink/trunk@171343 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[DevTools] Hide suggest box on mouse down.

BUG=361563

Review URL: https://codereview.chromium.org/227913006

git-svn-id: svn://svn.chromium.org/blink/trunk@171344 bbb929c8-8fbe-4397-9dbb-9b2b20218538