[heap] Introduce enum of garbage collection reasons.

test/cctest/test-decls.cc

 // Copyright 2007-2008 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 127 matching lines @@
   PostInitializeContext(context);
 }
 
 
 void DeclarationContext::Check(const char* source, int get, int set, int query,
                                Expectations expectations,
                                v8::Local<Value> value) {
   InitializeIfNeeded();
   // A retry after a GC may pollute the counts, so perform gc now
   // to avoid that.
-  CcTest::heap()->CollectGarbage(v8::internal::NEW_SPACE);
+  CcTest::CollectGarbage(v8::internal::NEW_SPACE);
   HandleScope scope(CcTest::isolate());
   TryCatch catcher(CcTest::isolate());
   catcher.SetVerbose(true);
   Local<Context> context = CcTest::isolate()->GetCurrentContext();
   MaybeLocal<Script> script = Script::Compile(
       context,
       String::NewFromUtf8(CcTest::isolate(), source, v8::NewStringType::kNormal)
           .ToLocalChecked());
   if (expectations == EXPECT_ERROR) {
     CHECK(script.IsEmpty());
@@ skipping 10 matching lines @@
       CHECK(value->Equals(context, result.ToLocalChecked()).FromJust());
     }
   } else {
     CHECK(expectations == EXPECT_EXCEPTION);
     CHECK(catcher.HasCaught());
     if (!value.IsEmpty()) {
       CHECK(value->Equals(context, catcher.Exception()).FromJust());
     }
   }
   // Clean slate for the next test.
-  CcTest::heap()->CollectAllAvailableGarbage();
+  CcTest::CollectAllAvailableGarbage();
 }
 
 
 void DeclarationContext::HandleGet(
     Local<Name> key, const v8::PropertyCallbackInfo<v8::Value>& info) {
   DeclarationContext* context = GetInstance(info.Data());
   context->get_count_++;
   info.GetReturnValue().Set(context->Get(key));
 }
 
@@ skipping 987 matching lines @@
                   Undefined(CcTest::isolate()));
     for (int i = 0; i < 4; i++) {
       context.Check("f()", EXPECT_EXCEPTION);
     }
     context.Check("%OptimizeFunctionOnNextCall(f);", EXPECT_RESULT,
                   Undefined(CcTest::isolate()));
 
     context.Check("'use strict'; f(); let x = 2; x", EXPECT_EXCEPTION);
   }
 }