Replace OS::MemCopy with OS::MemMove (just as fast but more flexible).

src/scanner.h

Index: src/scanner.h
diff --git a/src/scanner.h b/src/scanner.h
index e897f79872049205f762d0066e6a1de05057dfa0..92418f72b1b365ff94723df5a8d04f0072365b1e 100644
--- a/src/scanner.h
+++ b/src/scanner.h
@@ -215,7 +215,7 @@ class LiteralBuffer {
 
   void ExpandBuffer() {
     Vector<byte> new_store = Vector<byte>::New(NewCapacity(kInitialCapacity));
-    memcpy(new_store.start(), backing_store_.start(), position_);
+    OS::MemCopy(new_store.start(), backing_store_.start(), position_);
     backing_store_.Dispose();
     backing_store_ = new_store;
   }