Revert "Remove deprecated ShouldSelfOptimize machinery."

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index b752e2cd751ab3dad04ae3acbe13c60e46839392..ac31cfda545d0bd8e80ac8627056cf2e14d92f81 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -386,9 +386,14 @@ void FullCodeGenerator::EmitReturnSequence() {
       __ CallRuntime(Runtime::kTraceExit, 1);
     }
     // Pretend that the exit is a backwards jump to the entry.
-    int distance = masm_->pc_offset();
-    int weight =
-        Min(kMaxBackEdgeWeight, Max(1, distance / kCodeSizeMultiplier));
+    int weight = 1;
+    if (info_->ShouldSelfOptimize()) {
+      weight = FLAG_interrupt_budget / FLAG_self_opt_count;
+    } else {
+      int distance = masm_->pc_offset();
+      weight = Min(kMaxBackEdgeWeight,
+                   Max(1, distance / kCodeSizeMultiplier));
+    }
     EmitProfilingCounterDecrement(weight);
     Label ok;
     __ j(positive, &ok, Label::kNear);