Merge a number of assertion failure fixes to the 3.0 branch.

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
===================================================================
--- src/arm/macro-assembler-arm.cc	(revision 6703)
+++ src/arm/macro-assembler-arm.cc	(working copy)
@@ -1140,7 +1140,8 @@
 
   // Calculate new top and bail out if new space is exhausted. Use result
   // to calculate the new top.
-  add(scratch2, result, Operand(obj_size_reg));
+  add(scratch2, result, Operand(obj_size_reg), SetCC);
+  b(cs, gc_required);
   cmp(scratch2, Operand(ip));
   b(hi, gc_required);
   str(scratch2, MemOperand(topaddr));
@@ -1219,10 +1220,11 @@
   // to calculate the new top. Object size may be in words so a shift is
   // required to get the number of bytes.
   if ((flags & SIZE_IN_WORDS) != 0) {
-    add(scratch2, result, Operand(object_size, LSL, kPointerSizeLog2));
+    add(scratch2, result, Operand(object_size, LSL, kPointerSizeLog2), SetCC);
   } else {
-    add(scratch2, result, Operand(object_size));
+    add(scratch2, result, Operand(object_size), SetCC);
   }
+  b(cs, gc_required);
   cmp(scratch2, Operand(ip));
   b(hi, gc_required);