Bug 873136 - Only store the JSRuntime on the minor tracer once; r=billm

--HG--
extra : rebase_source : 3190b52824e68d38dbbefab0c202e408b8b51fe5
Bug 870496 - Purge moved objects in the NewObjectCache on minor GC; r=billm

--HG--
extra : rebase_source : 95da7731d4ea9ec023790a36de0a8cd7d68740f3
Bug 873142 - Do not shrink Arrays when tenuring; r=billm

The JITs assume that the capacity will not change between the initarray and the
actual initialization.

--HG--
extra : rebase_source : a7485d70a63ab8edea871c68696da9edf3872196
Bug 851057 - Implement generational GC support in IonMonkey; r=dvander