Revert "Do not rely on code patching on DBC for lazy deoptimization."

runtime/vm/stub_code_dbc.cc

Index: runtime/vm/stub_code_dbc.cc
diff --git a/runtime/vm/stub_code_dbc.cc b/runtime/vm/stub_code_dbc.cc
index 7fc405bdceaa622c055b35da01e05836ff7a3e4d..bf3783b1fd88c8a0035f08bca13fd7d98b952f29 100644
--- a/runtime/vm/stub_code_dbc.cc
+++ b/runtime/vm/stub_code_dbc.cc
@@ -49,7 +49,6 @@ void StubCode::GenerateRunExceptionHandlerStub(Assembler* assembler) {
 
 void StubCode::GenerateDeoptForRewindStub(Assembler* assembler) {
   __ DeoptRewind();
-  __ Trap();
 }
 
 
@@ -76,14 +75,12 @@ void StubCode::GenerateMegamorphicMissStub(Assembler* assembler) {
 // with something meaningful to make sure GC can scan the stack during
 // the last phase of deoptimization which materializes objects.
 void StubCode::GenerateDeoptimizeLazyFromReturnStub(Assembler* assembler) {
-  __ Deopt(0 /* unused */, 0 /* lazy */);
-  __ Trap();  // Not reached: pc is updated as part of deoptimization.
+  __ Trap();
 }
 
 
 void StubCode::GenerateDeoptimizeLazyFromThrowStub(Assembler* assembler) {
-  __ Deopt(0 /* unused */, 0 /* lazy */);
-  __ Trap();  // Not reached: pc is updated as part of deoptimization.
+  __ Trap();
 }