Add a check that we make progress during incremental marking

src/incremental-marking.cc

Index: src/incremental-marking.cc
diff --git a/src/incremental-marking.cc b/src/incremental-marking.cc
index f9575c3ba433393d67990a5edd45d08610c7dfeb..7dd687cce1a52ac96d010974e41d039f79af2e0d 100644
--- a/src/incremental-marking.cc
+++ b/src/incremental-marking.cc
@@ -699,7 +699,10 @@ void IncrementalMarking::ProcessMarkingDeque(intptr_t bytes_to_process) {
     int size = obj->SizeFromMap(map);
     unscanned_bytes_of_large_object_ = 0;
     VisitObject(map, obj, size);
-    bytes_to_process -= (size - unscanned_bytes_of_large_object_);
+    int delta = (size - unscanned_bytes_of_large_object_);
+    // FIXME: remove after http://crbug.com/381820 is resolved.
+    CHECK(0 < delta && delta <= bytes_to_process);

[Hannes Payer (out of office), 2014/07/09 08:53:49]

delta can be larger than bytes_to_process. I guess the first check is fine to
guarantee progress.

+    bytes_to_process -= delta;
   }
 }