Write-barrier verification on ARM.

runtime/vm/code_patcher_arm.cc

Index: runtime/vm/code_patcher_arm.cc
===================================================================
--- runtime/vm/code_patcher_arm.cc	(revision 42190)
+++ runtime/vm/code_patcher_arm.cc	(working copy)
@@ -7,6 +7,7 @@
 
 #include "vm/code_patcher.h"
 
+#include "vm/flow_graph_compiler.h"
 #include "vm/instructions.h"
 #include "vm/object.h"
 
@@ -103,7 +104,8 @@
 class EdgeCounter : public ValueObject {
  public:
   EdgeCounter(uword pc, const Code& code)
-      : end_(pc - kAdjust), object_pool_(Array::Handle(code.ObjectPool())) {
+      : end_(pc - FlowGraphCompiler::EdgeCounterIncrementSizeInBytes()),
+        object_pool_(Array::Handle(code.ObjectPool())) {
     // An IsValid predicate is complicated and duplicates the code in the
     // decoding function.  Instead we rely on decoding the pattern which
     // will assert partial validity.