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 ebeb6c613c9c817d10f01927970a5067eec77e87..c79d9c37a2ea0e25c3af5cfcef0f9d2d14355726 100644
--- a/src/compiler/ast-graph-builder.h
+++ b/src/compiler/ast-graph-builder.h
@@ -84,6 +84,9 @@ 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_;