Revert "Lazy deopt without code patching."

runtime/vm/code_patcher_mips.cc

Index: runtime/vm/code_patcher_mips.cc
diff --git a/runtime/vm/code_patcher_mips.cc b/runtime/vm/code_patcher_mips.cc
index 3ed9af34da4f6d63ed6c95af3b3ebd461b53aa0e..a4d0433a09944eae1a17eb3e4eb000b70f30b76e 100644
--- a/runtime/vm/code_patcher_mips.cc
+++ b/runtime/vm/code_patcher_mips.cc
@@ -29,8 +29,10 @@ 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::kDeoptCallLengthInBytes <= target);
+  CallPattern::InsertDeoptCallAt(start, target);
 }