Don't move the object start of objects on non-swept pages.

test/cctest/test-heap.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 4183 matching lines @@
   v8::Context::Scope cscope(context);
 
   v8::Local<v8::Value> result = CompileRun(
       "var locals = '';"
       "for (var i = 0; i < 512; i++) locals += 'var v' + i + '= 42;';"
       "eval('function f() {' + locals + 'return function() { return v0; }; }');"
       "interrupt();"  // This triggers a fake stack overflow in f.
       "f()()");
   CHECK_EQ(42.0, result->ToNumber()->Value());
 }
+
+
+TEST(ArrayShiftLazySweeping) {
+  i::FLAG_expose_gc = true;
+  i::FLAG_parallel_sweeping = false;
+  i::FLAG_concurrent_sweeping = false;
+  i::FLAG_lazy_sweeping = true;
+  CcTest::InitializeVM();
+  v8::HandleScope scope(CcTest::isolate());
+  Isolate* isolate = CcTest::i_isolate();
+  Heap* heap = isolate->heap();
+
+  v8::Local<v8::Value> result = CompileRun(
+      "var array = new Array(40000);"
+      "var tmp = new Array(100000);"
+      "gc();"
+      "array.shift();"
+      "array;");
+
+  Handle<JSObject> o =
+      v8::Utils::OpenHandle(*v8::Handle<v8::Object>::Cast(result));
+  CHECK(heap->InOldPointerSpace(o->elements()));
+  CHECK(heap->InOldPointerSpace(*o));
+  Page* page = Page::FromAddress(o->elements()->address());
+  CHECK(page->WasSwept() ||
+        Marking::IsBlack(Marking::MarkBitFrom(o->elements())));
+}