Fix tests that fail on GC stress tests.

test/cctest/test-api.cc

 // Copyright 2012 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 16040 matching lines @@
 
   i::String::WriteToFlat(*flat_string, uc16_buffer, 0, length);
   uc16_buffer[length] = 0;
 
   TestResource resource(uc16_buffer);
 
   flat_string->MakeExternal(&resource);
 
   CHECK(flat_string->IsTwoByteRepresentation());
 
-  // At this point, we should have a Cons string which is flat and ASCII,
-  // with a first half that is a two-byte string (although it only contains
-  // ASCII characters). This is a valid sequence of steps, and it can happen
-  // in real pages.
-
-  CHECK(string->IsOneByteRepresentation());
-  i::ConsString* cons = i::ConsString::cast(*string);
-  CHECK_EQ(0, cons->second()->length());
-  CHECK(cons->first()->IsTwoByteRepresentation());
+  // If the cons string has been short-circuited, skip the following checks.
+  if (!string.is_identical_to(flat_string)) {
+    // At this point, we should have a Cons string which is flat and ASCII,
+    // with a first half that is a two-byte string (although it only contains
+    // ASCII characters). This is a valid sequence of steps, and it can happen
+    // in real pages.
+    CHECK(string->IsOneByteRepresentation());
+    i::ConsString* cons = i::ConsString::cast(*string);
+    CHECK_EQ(0, cons->second()->length());
+    CHECK(cons->first()->IsTwoByteRepresentation());
+  }
 
   // Check that some string operations work.
 
   // Atom RegExp.
   Local<Value> reresult = CompileRun("str2.match(/abel/g).length;");
   CHECK_EQ(6, reresult->Int32Value());
 
   // Nonatom RegExp.
   reresult = CompileRun("str2.match(/abe./g).length;");
   CHECK_EQ(6, reresult->Int32Value());
@@ skipping 2241 matching lines @@
   i::Semaphore* sem_;
   volatile int sem_value_;
 };
 
 
 THREADED_TEST(SemaphoreInterruption) {
   ThreadInterruptTest().RunTest();
 }
 
 #endif  // WIN32