[turbofan] Implement OSR for outer loops.

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 27b8e3063c40d70c0da45aea47b6868e6fcbbbb5..3724f9192851f9c3879fd3284006d6af8a2b7251 100644
--- a/src/compiler/ast-graph-builder.h
+++ b/src/compiler/ast-graph-builder.h
@@ -114,6 +114,8 @@ class AstGraphBuilder : public StructuredGraphBuilder, public AstVisitor {
   // Builder for stack-check guards.
   Node* BuildStackCheck();
 
+  bool IsOsrLoopEntry(IterationStatement* stmt);
+
 #define DECLARE_VISIT(type) virtual void Visit##type(type* node) OVERRIDE;
   // Visiting functions for AST nodes make this an AstVisitor.
   AST_NODE_LIST(DECLARE_VISIT)
@@ -140,6 +142,9 @@ class AstGraphBuilder : public StructuredGraphBuilder, public AstVisitor {
   SetOncePointer<Node> function_closure_;
   SetOncePointer<Node> function_context_;
 
+  // The node representing the OSR entry into the loop, if any.
+  SetOncePointer<Node> osr_loop_entry_;
+
   // Result of loop assignment analysis performed before graph creation.
   LoopAssignmentAnalysis* loop_assignment_analysis_;