Bug 860560: make sure that defaultEngine and currentEngine stay in sync, r=gavin

--HG--
extra : rebase_source : 2a3169621b8cedf1382d738bd67072dae77cb4ce
Bug 854478: remove support for automatically converting Sherlock-format search engines that were dropped into the profile directory, r=MattN

--HG--
extra : transplant_source : 2%EBl%CE1W%3E%A2%B3JK0%10M%0B%AF%87%C5H%AB
Bug 862143: remove support for loading sherlock files from disk, r=MattN

--HG--
extra : transplant_source : %0D%EC%3F%1E%1At%B5%23J%1F3V%F4%C8Uq%93l%F0%40
Test case for bug 880724
bug 868599 - update gaia.json with repo_path. r=jgriffin
Bug 878875 - Import PannerNode tests from Blink. r=ehsan

Imported from Blink SVN revision 152035
Bug 878875 - Port Blink's LayoutTest for PannerNode to mochitest-plain. r=ehsan
Bug 880392 - Fix use-after free with exact rooting in XPCShell; r=sfink

--HG--
extra : rebase_source : a509e84b7165b8a40f4a06e006dfc614665eef2c
Bug 798438 - Use a dictionary to set context options instead of an nsIPropertyBag r=bz
Bug 879998 - Remove some dead code in content/events r=smaug
Backout 498f79c24e70 (bug 860560) for browser-chrome bustage
Bug 880539 - Fix CodeGenerator::guardTypeSet to handle MagicArgs type. r=bhackett
Bug 867567 - JavaScript Error: "TypeError: focused is null". r=kats
Bug 877965 - In asm.js mode, use the last return statement instead of the last statement to find the return type of a function. r=luke
Bug 877965 - Ignore empty statements in var declarations in asm.js mode. r=luke
Bug 878154 - about:plugins: plugin status is not localizable. r=bsmedberg
Bug 878495 - In shell, print "[native code]" for native functions. r=luke
Bug 880662 - Remove unused variable from YCbCrImageDataDeserializerBase::IsValid(). r=nical
Bug 878491 - Save about:home top padding in BrowserApp instead of AboutHome fragment. r=lucasr
Merge m-c to inbound.