Backed out 3 changesets (bug 956961) for non-unified build bustage

Backed out changeset f1be89cb58b9 (bug 956961)
Backed out changeset 272b01e4f856 (bug 956961)
Backed out changeset 56907af18c66 (bug 956961)
Bug 1031129 - Fix ObjdirMismatchException logic to throw properly on m-c. r=gps
Bug 1030717 -  Don't try to create the mach state directory until it's actually needed. r=gps
Bug 1031132 - Refactor mach environment to use logic from MachCommandBase instead of its own. r=gps

Also don't print section titles when there is nothing under them, and move
move the ObjdirMismatchException handling to MachCommandBase.
Bug 1031180 - Fallback to checking whether the directory mach lives in contains mach_bootstrap.py. r=gps
Bug 762358 - Re-run configure when mozconfig changed in a significant way. r=gps

This adds a format option to mach environment and uses it in client.mk to
create a .mozconfig.json in the objdir, containing all the relevant data
from mozconfig. If the mozconfig doesn't change in a way that alters that
data, we still skip configure.

At the same time, use mach environment in place of mozconfig2configure and
mozconfig2client-mk, which makes us now have only one mozconfig reader.

Also, in the mozconfig reader, keep track of environment variables (as
opposed to shell variables), so that changes such as a variable that was
exported not being exported anymore is spotted. At the opposite, in order
for irrelevant environment variable changes not to incur in re-running
configure, only a set of environment variables are stored when they are
unmodified. Otherwise, changes such as using a different terminal window,
or even rebooting, would trigger reconfigures.

Finally, make mach environment emit both MOZ_OBJDIR and OBJDIR for
client.mk, and cleanup some objdir-related things in client.mk..
At the same time, make the mozconfig reader take MOZ_OBJDIR from the
environment if it is defined there and not in the mozconfig.
Bug 1033033 - Don't access the device_manager during __init__, r=mdas
Bug 1028187 - Enable IndexedDB for about:looppanel and about:loopconversation, sharing an origin r=bz
Bug 1009312 - Remove duplicate calls to addActorPool. r=dcamp
Bug 1015665 - Do not store function calls in CallWatcherActor unless needed. r=vp
Bug 1023339 - Fixed in-content preferences clickable areas width to cover only the element and its label. r=mconley
Bug 1016613 -  Replaced RemoteTabsPanel view with ViewStub in tabs_panel.xml and created new layout file to inflate the ViewStub when user clicks on 3rd button in TabsPanel. r=mcomella
Bug 1034191 - Make nsDependentJSString users work with Latin1 strings and nursery-allocated strings. r=bz
Add missing includes to widget/gonk/nsWindow.cpp so that it continues to compile after my upcoming commits. r=mstange on IRC, no bug
Bug 1034574 - Remove SVGContentUtils::CoordToFloat's aPresContext argument. r=longsonr
Bug 1034115 - Stop creating CSS-px-to-dev-pixel matrices when doing SVG hit-testing. r=longsonr
Bug 1023277 - Dropdown for mail view selector uses menuitem[type="radio"] causing "All" and "Unread" to show no text when hovered instead of highlighted text with Win7 Aero Themes r=Dão
Bug 1031978 - Suppress -Wmismatched-tags clang warnings in third-party code: libstagefright. r=cajbir
Bug 1023141 - query ril.ecclist per dial request - part 3 - fix xpcshell. r=aknow
Bug 1018154 - part 1: replace blocking of security principal inheriting with onpaste handler, r=dao