Revert "Lazy deopt without code patching."

runtime/vm/code_patcher_arm64.cc

Index: runtime/vm/code_patcher_arm64.cc
diff --git a/runtime/vm/code_patcher_arm64.cc b/runtime/vm/code_patcher_arm64.cc
index 658f4064bcd9ee7e020de67e52a8e599c7cbe880..76b959b75840864ead5b7f901ee7cf184e288809 100644
--- a/runtime/vm/code_patcher_arm64.cc
+++ b/runtime/vm/code_patcher_arm64.cc
@@ -70,8 +70,10 @@ void CodePatcher::PatchPoolPointerCallAt(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::kDeoptCallLengthInBytes <= target);
+  CallPattern::InsertDeoptCallAt(start, target);
 }