Simplify and fix code aging.

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index 9c69e8e7553b96bbc7443bb35e18f9dcf73d07e9..7cb402e636b25903a995206b9cc48f1d82ef144c 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -149,15 +149,12 @@ void FullCodeGenerator::Generate() {
   // function calls.
   if (!info->is_classic_mode() || info->is_native()) {
     Label ok;
-    Label begin;
-    __ bind(&begin);
     __ cmp(r5, Operand(0));
     __ b(eq, &ok);
     int receiver_offset = info->scope()->num_parameters() * kPointerSize;
     __ LoadRoot(r2, Heap::kUndefinedValueRootIndex);
     __ str(r2, MemOperand(sp, receiver_offset));
     __ bind(&ok);
-    ASSERT_EQ(kSizeOfFullCodegenStrictModePrologue, ok.pos() - begin.pos());
   }
 
   // Open a frame scope to indicate that there is a frame on the stack.  The
@@ -167,6 +164,7 @@ void FullCodeGenerator::Generate() {
 
   int locals_count = info->scope()->num_stack_slots();
 
+  info->set_prologue_offset(masm_->pc_offset());
   // The following four instructions must remain together and unmodified for
   // code aging to work properly.
   __ stm(db_w, sp, r1.bit() | cp.bit() | fp.bit() | lr.bit());