[turbofan] Port Crankshaft's weak objects mechanism to TurboFan.

test/cctest/cctest.status

Index: test/cctest/cctest.status
diff --git a/test/cctest/cctest.status b/test/cctest/cctest.status
index 7abc57b925c3044d89a1aec5a3f74d779597afc6..804d9fb748b48124a3f8b21a6100b98c6fab3ef1 100644
--- a/test/cctest/cctest.status
+++ b/test/cctest/cctest.status
@@ -121,10 +121,13 @@
   # optimized and hence scripts don't "return" the correct value. Fix this.
   'test-compiler/CompileFunctionInContext*': [PASS, NO_VARIANTS],
 
+  # TODO(bmeurer): TurboFan embeds strong references to all kinds of objects
+  # via deoptimization data (Crankshaft also does this, but lack proper test
+  # coverage).
+  'test-heap/ObjectsInOptimizedCodeAreWeak': [PASS, NO_VARIANTS],
+
   # TurboFan doesn't support allocation sites currently.
-  'test-heap/CellsInOptimizedCodeAreWeak': [PASS, NO_VARIANTS],
   'test-heap/EnsureAllocationSiteDependentCodesProcessed': [PASS, NO_VARIANTS],
-  'test-heap/ObjectsInOptimizedCodeAreWeak': [PASS, NO_VARIANTS],
   'test-heap/OptimizedPretenuringAllocationFolding': [PASS, NO_VARIANTS],
   'test-heap/OptimizedPretenuringdoubleArrayLiterals': [PASS, NO_VARIANTS],
   'test-heap/OptimizedPretenuringDoubleArrayProperties': [PASS, NO_VARIANTS],