Fire 'stack' getter of error objects after GC.

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 143 matching lines @@
     if (!value.IsEmpty()) {
       CHECK_EQ(value, result);
     }
   } else {
     CHECK(expectations == EXPECT_EXCEPTION);
     CHECK(catcher.HasCaught());
     if (!value.IsEmpty()) {
       CHECK_EQ(value, catcher.Exception());
     }
   }
+  HEAP->CollectAllAvailableGarbage();  // Clean slate for the next test.
 }
 
 
 v8::Handle<Value> DeclarationContext::HandleGet(Local<String> key,
                                                 const AccessorInfo& info) {
   DeclarationContext* context = GetInstance(info);
   context->get_count_++;
   return context->Get(key);
 }
 
@@ skipping 724 matching lines @@
                   EXPECT_ERROR);
   }
 
   { SimpleContext context;
     context.Check("const x = 1; x",
                   EXPECT_RESULT, Number::New(1));
     context.Check("function x() { return 2 }; x()",
                   EXPECT_ERROR);
   }
 }