Simplify isolates access during stack iteration (WAS: Move SafeStackFrameIterator::active_count_...)

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index a9962c3f9fd636d45ddcfb1e51890a727dd95b7e..638658ba7a67a21a4c6cc68cb05765c4cfc4ad5c 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -316,6 +316,8 @@ typedef List<HeapObject*, PreallocatedStorage> DebugObjectCache;
   /* AstNode state. */                                                         \
   V(unsigned, ast_node_id, 0)                                                  \
   V(unsigned, ast_node_count, 0)                                               \
+  /* SafeStackFrameIterator activations count. */                              \
+  V(int, safe_stack_iterator_counter, 0)                                       \
   ISOLATE_PLATFORM_INIT_LIST(V)                                                \
   ISOLATE_LOGGING_INIT_LIST(V)                                                 \
   ISOLATE_DEBUGGER_INIT_LIST(V)
@@ -1142,7 +1144,7 @@ class SaveContext BASE_EMBEDDED {
     isolate->set_save_context(this);
 
     // If there is no JS frame under the current C frame, use the value 0.
-    JavaScriptFrameIterator it;
+    JavaScriptFrameIterator it(isolate);
     js_sp_ = it.done() ? 0 : it.frame()->sp();
   }