Use GetCodeFromTargetAddress everywhere, uniformly.

src/objects.cc

Index: src/objects.cc
===================================================================
--- src/objects.cc	(revision 2887)
+++ src/objects.cc	(working copy)
@@ -4967,7 +4967,7 @@
        !it.done(); it.next()) {
     Address ic_addr = it.rinfo()->target_address();
     ASSERT(ic_addr != NULL);
-    HeapObject* code = HeapObject::FromAddress(ic_addr - Code::kHeaderSize);
+    HeapObject* code = Code::GetCodeFromTargetAddress(ic_addr);
     ASSERT(code->IsHeapObject());
     it.rinfo()->set_target_object(code);
   }
@@ -4980,7 +4980,7 @@
       if (it.rinfo()->IsCallInstruction()) {
         Address addr = it.rinfo()->call_address();
         ASSERT(addr != NULL);
-        HeapObject* code = HeapObject::FromAddress(addr - Code::kHeaderSize);
+        HeapObject* code = Code::GetCodeFromTargetAddress(addr);
         ASSERT(code->IsHeapObject());
         it.rinfo()->set_call_object(code);
       }