Improve positions tracking inside the HGraphBuilder.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 5956baad8851d458bea783c1bbce0adc2aabe38b..886c0ac114538c0298b02ea9ceaf4401edf9e60c 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -1148,6 +1148,14 @@ class Isolate {
   // Given an address occupied by a live code object, return that object.
   Object* FindCodeObject(Address a);
 
+  int NextOptimizationId() {
+    int id = next_optimization_id_++;
+    if (!Smi::IsValid(next_optimization_id_)) {
+      next_optimization_id_ = 0;
+    }
+    return id;
+  }
+
  private:
   Isolate();
 
@@ -1378,6 +1386,8 @@ class Isolate {
   // Counts deopt points if deopt_every_n_times is enabled.
   unsigned int stress_deopt_count_;
 
+  int next_optimization_id_;
+
   friend class ExecutionAccess;
   friend class HandleScopeImplementer;
   friend class IsolateInitializer;