[turbofan] Support initial step-in through debugger statement.

test/cctest/cctest.status

 # Copyright 2011 the V8 project authors. All rights reserved.
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@@ skipping 84 matching lines @@
 
   # Some tests are just too slow to run for now.
   'test-api/Threading*': [PASS, NO_VARIANTS],
   'test-heap/IncrementalMarkingStepMakesBigProgressWithLargeObjects': [PASS, NO_VARIANTS],
   'test-heap-profiler/ManyLocalsInSharedContext': [PASS, NO_VARIANTS],
   'test-debug/ThreadedDebugging': [PASS, NO_VARIANTS],
   'test-debug/DebugBreakLoop': [PASS, NO_VARIANTS],
   # BUG(3742).
   'test-mark-compact/MarkCompactCollector': [PASS, ['arch==arm', NO_VARIANTS]],
 
-  # TODO(jarin/mstarzinger): Investigate debugger issues with TurboFan.
-  'test-debug/DebugStepNatives': [PASS, NO_VARIANTS],
-  'test-debug/DebugStepFunctionApply': [PASS, NO_VARIANTS],
-  'test-debug/DebugStepFunctionCall': [PASS, NO_VARIANTS],
-
   # TODO(jarin): Cannot lazy-deoptimize from conversions before comparisons.
   'test-js-typed-lowering/OrderCompareEffects': [SKIP],
 
   # TODO(jochen): Reenable after we removed the CHECK() from the marking queue.
   'test-mark-compact/MarkingDeque': [SKIP],
 
   'test-heap/TestInternalWeakLists': [PASS, ['arch==arm', NO_VARIANTS]],
   'test-heap/TestInternalWeakListsTraverseWithGC': [PASS, ['arch==arm', NO_VARIANTS]],
 
   ############################################################################
@@ skipping 281 matching lines @@
 ##############################################################################
 ['arch == ppc and simulator_run == True or arch == ppc64 and simulator_run == True', {
 
   # Pass but take too long with the simulator.
   'test-api/Threading1': [PASS, SLOW],
   'test-api/Threading2': [PASS, SLOW],
   'test-api/ExternalArrays': [PASS, SLOW],
 
 }],  # 'arch == ppc64 and simulator_run == True'
 ]