DevTools extensions: forward keyboard shortcuts to DevTools

DevTools extensions: forward keyboard shortcuts to DevTools

This adds keyboard event handler that forwards keyboard extensions
that look like shortcuts to DevTools, so these may be handled as
global shortcuts by DevTools.

BUG=160930
R=apavlov@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=153786

[apavlov, 2013-07-09 06:51:58]

LGTM with nits

https://codereview.chromium.org/18835002/diff/1/Source/devtools/front_end/Ext...
File Source/devtools/front_end/ExtensionAPI.js (right):

https://codereview.chromium.org/18835002/diff/1/Source/devtools/front_end/Ext...
Source/devtools/front_end/ExtensionAPI.js:732: if (!event.ctrlKey &&
!event.altKey && !event.metaKey && !/^F\d+$/.test(event.keyIdentifier) &&
event.keyIdentifier != Esc)
!==

https://codereview.chromium.org/18835002/diff/1/Source/devtools/front_end/Ext...
Source/devtools/front_end/ExtensionAPI.js:748: 
Would you want to forward "keyup" as well?

https://codereview.chromium.org/18835002/diff/1/Source/devtools/front_end/Ext...
File Source/devtools/front_end/ExtensionServer.js (right):

https://codereview.chromium.org/18835002/diff/1/Source/devtools/front_end/Ext...
Source/devtools/front_end/ExtensionServer.js:574: if (!message.ctrlKey &&
!message.altKey && !message.metaKey && !/^F\d+$/.test(message.keyIdentifier) &&
message.keyIdentifier != Esc)
!==

https://codereview.chromium.org/18835002/diff/1/Source/devtools/front_end/Ext...
Source/devtools/front_end/ExtensionServer.js:576: // Fool around closure
compiler -- it has it's own notion of both KeyboardEvent constructor
"it's" -> "its"

[caseq, 2013-07-09 14:23:37]

Committed patchset #2 manually as r153786 (presubmit successful).