Revert "Lazy deopt without code patching."

runtime/vm/flow_graph_compiler_arm64.cc

Index: runtime/vm/flow_graph_compiler_arm64.cc
diff --git a/runtime/vm/flow_graph_compiler_arm64.cc b/runtime/vm/flow_graph_compiler_arm64.cc
index 405d974883c0457b4cbcda341bd94c98ee663ce4..ac4d66df0b5f5754694a2d253324c1a80b11b65f 100644
--- a/runtime/vm/flow_graph_compiler_arm64.cc
+++ b/runtime/vm/flow_graph_compiler_arm64.cc
@@ -1106,6 +1106,21 @@ void FlowGraphCompiler::CompileGraph() {
   __ brk(0);
   ASSERT(assembler()->constant_pool_allowed());
   GenerateDeferredCode();
+
+  BeginCodeSourceRange();
+  if (is_optimizing() && !FLAG_precompiled_mode) {
+    // Leave enough space for patching in case of lazy deoptimization.
+    for (intptr_t i = 0;
+      i < CallPattern::kDeoptCallLengthInInstructions;
+      ++i) {
+      __ orr(R0, ZR, Operand(R0));  // nop
+    }
+    lazy_deopt_return_pc_offset_ = assembler()->CodeSize();
+    __ BranchPatchable(*StubCode::DeoptimizeLazyFromReturn_entry());
+    lazy_deopt_throw_pc_offset_ = assembler()->CodeSize();
+    __ BranchPatchable(*StubCode::DeoptimizeLazyFromThrow_entry());
+  }
+  EndCodeSourceRange(TokenPosition::kDartCodeEpilogue);
 }