Reapplying changes from r4318

src/heap-inl.h

Index: src/heap-inl.h
===================================================================
--- src/heap-inl.h	(revision 4401)
+++ src/heap-inl.h	(working copy)
@@ -240,6 +240,27 @@
 }
 
 
+void Heap::MoveBlock(Object** dst, Object** src, size_t byte_size) {
+  ASSERT(IsAligned<size_t>(byte_size, kPointerSize));
+
+  int size_in_words = byte_size / kPointerSize;
+
+  if ((dst < src) || (dst >= (src + size_in_words))) {
+    ASSERT((dst >= (src + size_in_words)) ||
+           ((OffsetFrom(reinterpret_cast<Address>(src)) -
+             OffsetFrom(reinterpret_cast<Address>(dst))) >= kPointerSize));
+
+    Object** end = src + size_in_words;
+
+    while (src != end) {
+      *dst++ = *src++;
+    }
+  } else {
+    memmove(dst, src, byte_size);
+  }
+}
+
+
 void Heap::ScavengeObject(HeapObject** p, HeapObject* object) {
   ASSERT(InFromSpace(object));