Merge r9145 from the bleeding_edge to the 3.3 branch.

src/spaces-inl.h

Index: src/spaces-inl.h
===================================================================
--- src/spaces-inl.h	(revision 9145)
+++ src/spaces-inl.h	(working copy)
@@ -155,7 +155,8 @@
 
 uint32_t Page::GetRegionMaskForSpan(Address start, int length_in_bytes) {
   uint32_t result = 0;
-  if (length_in_bytes >= kPageSize) {
+  static const intptr_t kRegionMask = (1 << kRegionSizeLog2) - 1;
+  if (length_in_bytes + (OffsetFrom(start) & kRegionMask) >= kPageSize) {
     result = kAllRegionsDirtyMarks;
   } else if (length_in_bytes > 0) {
     int start_region = GetRegionNumberForAddress(start);