Merge v8_optimized_debug 1 and 2

src/vector.h

Index: src/vector.h
diff --git a/src/vector.h b/src/vector.h
index a4fdb1060efa195056e5c9c6e7df11065c4e584a..895c61b4ece176acfe8820f13779140ff3c552c2 100644
--- a/src/vector.h
+++ b/src/vector.h
@@ -31,9 +31,9 @@ class Vector {
   // Returns a vector using the same backing storage as this one,
   // spanning from and including 'from', to but not including 'to'.
   Vector<T> SubVector(int from, int to) {
-    SLOW_DCHECK(to <= length_);
-    SLOW_DCHECK(from < to);
     DCHECK(0 <= from);
+    SLOW_DCHECK(from < to);
+    SLOW_DCHECK(static_cast<unsigned>(to) <= static_cast<unsigned>(length_));
     return Vector<T>(start() + from, to - from);
   }