Reviewed by Oliver Hunt.

        Filter all Heap collection through a common reset function, in
        preparation for adding features triggered by collection.
        https://bugs.webkit.org/show_bug.cgi?id=53396
        
        SunSpider reports no change.

        * runtime/Heap.cpp:
        (JSC::Heap::reportExtraMemoryCostSlowCase): When we're over the extraCost
        limit, just call collectAllGarbage() instead of rolling our own special
        way of resetting the heap. In theory, this may be slower in some cases,
        but it also fixes cases of pathological heap growth that we've seen,
        where the only objects being allocated are temporary and huge
        (<rdar://problem/8885843>).

        (JSC::Heap::allocate):
        (JSC::Heap::collectAllGarbage): Use the shared reset function.

        (JSC::Heap::reset):
        * runtime/Heap.h: Carved a new shared reset function out of the old
        collectAllGarbage.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@77094 268f45cc-cd09-0410-ab3c-d52691b4dbfc