Bug 933074 - Allow a pldhash to be reasonably overloaded if it cannot be grown further.  r=jorendorff.

--HG--
extra : rebase_source : 0760f78d5332b4791899c1db649493eeca10b978
Bug 933605 (part 1) - Remove DEBUG_XXXbrendan-only code.  r=jorendorff.

--HG--
extra : rebase_source : 8ebc751e246cf133f899a8563e75f9bff77d9eda
Bug 933605 (part 2) - Don't declare all vars at the top of functions in pldhash.cpp.  r=jorendorff.

--HG--
extra : rebase_source : 53da17b46bd986ceefbc66f23e43d2f5b7290fad