Address MSVS 2013 warning C4146: unary minus operator applied to unsigned type, result still unsign…

runtime/vm/object_set.h

Index: runtime/vm/object_set.h
diff --git a/runtime/vm/object_set.h b/runtime/vm/object_set.h
index 6f687a9663af987907ae5376147e8e83dffbf09f..d48a146e0bf5de571c4df7b78da5634f43de5f55 100644
--- a/runtime/vm/object_set.h
+++ b/runtime/vm/object_set.h
@@ -31,7 +31,7 @@ class ObjectSet {
     ASSERT(start_ <= end_);
     size_ = SizeFor((end_ - start_) >> kWordSizeLog2);
     allocation_ = new uword[size_];
-    data_ = &allocation_[-((start >> kWordSizeLog2) / kBitsPerWord)];
+    data_ = &allocation_[0 - ((start >> kWordSizeLog2) / kBitsPerWord)];

[koda, 2014/09/25 21:31:28]

Consider creating a local intptr_t for the expression, and then negate it. It
may not be obvious to the reader that this subtraction produces a signed result
(even if it satisfies the compiler).

     ASSERT(allocation_ == &data_[(start >> kWordSizeLog2) / kBitsPerWord]);
     Clear();
   }