https://bugs.webkit.org/show_bug.cgi?id=123629
<rdar://problem/15365476>

Reviewed by Michael Saboff.
        
The problem here is two-fold:

1) A watchpoint (i.e. ProfiledCodeBlockJettisoningWatchpoint) may be fired after we
have cleared the CodeBlock for all or some Executables.  This means that doing
codeBlock->baselineVersion() would either crash or return a bogus CodeBlock, since
there wasn't a baseline code block reachable from the Executable anymore.  The
solution is that we shouldn't be asking for the baseline code block reachable from
the owning executable (what baselineVersion did), but instead we should be asking
for the baseline version reachable from the code block being watchpointed (basically
what CodeBlock::alternative() did).

2) If dealing with inlined code, baselienCodeBlockForOriginAndBaselineCodeBlock()
may return null, for the same reason as above - we might have cleared the baseline
codeblock for the executable that was inlined.  The solution is to just not do
profiling if there isn't a baseline code block anymore.

* bytecode/CodeBlock.cpp:
(JSC::CodeBlock::baselineAlternative):
(JSC::CodeBlock::baselineVersion):
(JSC::CodeBlock::jettison):
* bytecode/CodeBlock.h:
* bytecode/CodeBlockJettisoningWatchpoint.cpp:
(JSC::CodeBlockJettisoningWatchpoint::fireInternal):
* bytecode/ProfiledCodeBlockJettisoningWatchpoint.cpp:
(JSC::ProfiledCodeBlockJettisoningWatchpoint::fireInternal):
* dfg/DFGOSRExitBase.cpp:
(JSC::DFG::OSRExitBase::considerAddingAsFrequentExitSiteSlow):
* jit/AssemblyHelpers.h:
(JSC::AssemblyHelpers::AssemblyHelpers):
* runtime/Executable.cpp:
(JSC::FunctionExecutable::baselineCodeBlockFor):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@158459 268f45cc-cd09-0410-ab3c-d52691b4dbfc