Heap::waitForCollector() is one of 2 clients of Heap::stopIfNecessarySlow(unsigned oldState). The other client, Heap::stopIfNecessarySlow() sets m_mutatorDidRun to true after calling Heap::stopIfNecessarySlow(unsigned oldState). Heap::waitForCollector() needs to do the same. Constraint solvers rely on this. rdar://78326474
Created attachment 433099 [details] proposed patch.
Thanks for the review. Landed in r279689: <http://trac.webkit.org/r279689>.