Bug 875305 - Remove slow CSS selectors for WebVTT. r=bz, a=akeybl

Bug 833388 added rules to the default stylesheet for styling WebVTT
cues displayed in an html video element. The code to drive this
didn't land for Firefox 22, and the rules don't follow best practices
for performance and could slow down page rendering.

This commit just removes the rules since they're not used.
Bug 875252 - Make type=file click() to work (again) even when the element isn't in the DOM. r=jst, a=akeybl
Bug 875609 - Refactor jump list code to decode images on the main thread. r=jimm. a=akeybl
Bug 870529 - JumpListStartup not being called on delay startup causing no shortcut maintenance. r=jimm. a=akeybl
Bug 878037 - Make static image requests (imgRequestProxyStatic) Clone correctly when the concrete-type Clone override is called. r=seth a=akeybl
Bug 846986 - Include jsscriptinlines.h in SPSProfiler.cpp so that it builds in no-jit configurations. r=jandem, a=akeybl