[debugger] fix debug-evaluate wrt shadowed context var.

test/mjsunit/es6/debug-evaluate-arrow-function-receiver.js

Index: test/mjsunit/es6/debug-evaluate-arrow-function-receiver.js
diff --git a/test/mjsunit/es6/debug-evaluate-arrow-function-receiver.js b/test/mjsunit/es6/debug-evaluate-arrow-function-receiver.js
new file mode 100644
index 0000000000000000000000000000000000000000..ce7201df9ce74c6d6ca146eb9431623cddfc1cf9
--- /dev/null
+++ b/test/mjsunit/es6/debug-evaluate-arrow-function-receiver.js
@@ -0,0 +1,116 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --expose-debug-as debug
+
+// Test that debug-evaluate can find the correct this value for an arrow
+// function, if "this" is referenced within the arrow function scope.
+
+Debug = debug.Debug
+
+var break_count = 0;
+var exception = null;
+
+function listener(event, exec_state, event_data, data) {
+  if (event != Debug.DebugEvent.Break) return;
+  try {
+    for (var i = 0; i < exec_state.frameCount() - 1; i++) {
+      var frame = exec_state.frame(i);
+      var this_value = frame.evaluate("this").value();
+      var expected = frame.sourceLineText().match(/\/\/ (.*$)/)[1];
+      print(expected, this_value, frame.sourceLineText());
+      assertEquals(String(expected), String(this_value));
+    }
+    break_count++;
+  } catch (e) {
+    exception = e;
+    print(e + e.stack);
+  }
+}
+
+// Context-allocated receiver.
+function f() {
+  debugger;                          // foo
+  return () => {
+    debugger;                        // foo
+    with ({}) {
+      return () => {
+        debugger;                    // foo
+        try {
+          throw new Error();
+        } catch (e) {
+          return () => {
+            (() => this);            // bind this.
+            debugger;                // foo
+            return () => {
+              debugger;              // undefined
+              return g.call("goo");  // undefined
+            }
+          };
+        }
+      };
+    }
+  };
+}
+
+// Stack-allocated receiver.
+function g() {
+  debugger;                        // goo
+  return () => {
+    debugger;                      // undefined
+    with ({}) {
+      return () => {
+        debugger;                  // undefined
+        try {
+          throw new Error();
+        } catch (e) {
+          return () => {
+            debugger;              // undefined
+            return f.call("foo");  // undefined
+          };
+        }
+      };
+    }
+  };
+}
+
+Debug.setListener(listener);
+
+var h = f.call("foo");
+for (var i = 0; i < 20; i++) h = h();
+var h = g.call("goo");
+for (var i = 0; i < 20; i++) h = h();
+
+function x() {
+  (() => this);      // bind this.
+  function y() {
+    (() => {
+      (() => this);  // bind this.
+      debugger;      // Y
+     })();           // Y
+  }
+  y.call("Y");       // X
+}
+x.call("X");
+
+function u() {
+  (() => this);
+  function v() {
+    (() => {
+      debugger;      // undefined
+     })();           // V
+  }
+  v.call("V");       // U
+}
+u.call("U");
+
+(() => {
+  (() => this);
+  debugger;          // [object global]
+})();
+
+Debug.setListener(null);
+
+assertEquals(55, break_count);
+assertNull(exception);