Revert "Lazy deopt without code patching."

runtime/vm/code_patcher_arm.cc

Index: runtime/vm/code_patcher_arm.cc
diff --git a/runtime/vm/code_patcher_arm.cc b/runtime/vm/code_patcher_arm.cc
index 7640a5f25030a1db614c716a0493c2942072e227..62775bf903be24e40288798cd397aefef32bcfbe 100644
--- a/runtime/vm/code_patcher_arm.cc
+++ b/runtime/vm/code_patcher_arm.cc
@@ -30,8 +30,10 @@ void CodePatcher::PatchStaticCallAt(uword return_address,
 }
 
 
-void CodePatcher::InsertDeoptimizationCallAt(uword start) {
-  UNREACHABLE();
+void CodePatcher::InsertDeoptimizationCallAt(uword start, uword target) {
+  // The inserted call should not overlap the lazy deopt jump code.
+  ASSERT(start + CallPattern::DeoptCallPatternLengthInBytes() <= target);
+  CallPattern::InsertDeoptCallAt(start, target);
 }