[heap] Introduce enum of garbage collection reasons.

test/cctest/test-symbols.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 53 matching lines @@
     CHECK_GT(symbols[i]->Hash(), 0u);
     os << Brief(*symbols[i]) << "\n";
 #if OBJECT_PRINT
     symbols[i]->Print(os);
 #endif
 #if VERIFY_HEAP
     symbols[i]->ObjectVerify();
 #endif
   }
 
-  CcTest::heap()->CollectGarbage(i::NEW_SPACE);
-  CcTest::heap()->CollectAllGarbage();
+  CcTest::CollectGarbage(i::NEW_SPACE);
+  CcTest::CollectAllGarbage(i::Heap::kFinalizeIncrementalMarkingMask);
 
   // All symbols should be distinct.
   for (int i = 0; i < kNumSymbols; ++i) {
     CHECK(symbols[i]->SameValue(*symbols[i]));
     for (int j = i + 1; j < kNumSymbols; ++j) {
       CHECK(!symbols[i]->SameValue(*symbols[j]));
     }
   }
 }