Model exceptional edges from call nodes in TurboFan.

src/compiler/ast-graph-builder.h

Index: src/compiler/ast-graph-builder.h
diff --git a/src/compiler/ast-graph-builder.h b/src/compiler/ast-graph-builder.h
index fa72f1ad36166428965268663584bd9cc5241cdc..661626d97d41b05549d770596929fb679f716f71 100644
--- a/src/compiler/ast-graph-builder.h
+++ b/src/compiler/ast-graph-builder.h
@@ -90,6 +90,9 @@ class AstGraphBuilder : public AstVisitor {
   SetOncePointer<Node> function_closure_;
   SetOncePointer<Node> function_context_;
 
+  // Tracks how many try-blocks are currently entered.
+  int try_nesting_level_;
+
   // Temporary storage for building node input lists.
   int input_buffer_size_;
   Node** input_buffer_;