[debugger] debug-evaluate should not not modify local values.

test/mjsunit/debug-evaluate-closure.js

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 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Flags: --expose-debug-as debug --allow-natives-syntax
+// Flags: --debug-eval-readonly-locals
 
 Debug = debug.Debug;
 var listened = false;
 
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
     assertEquals("goo", exec_state.frame(0).evaluate("goo").value());
-    exec_state.frame(0).evaluate("goo = 'goo foo'");
+    exec_state.frame(0).evaluate("goo = 'goo foo'");  // no effect
     assertEquals("bar return", exec_state.frame(0).evaluate("bar()").value());
-    // Check that calling bar() has no effect to context-allocated variables.
-    // TODO(yangguo): reevaluate this if we no longer update context from copy.
-    assertEquals("inner", exec_state.frame(0).evaluate("inner").value());
-    assertEquals("outer", exec_state.frame(0).evaluate("outer").value());
+    assertEquals("inner bar", exec_state.frame(0).evaluate("inner").value());
+    assertEquals("outer bar", exec_state.frame(0).evaluate("outer").value());
 
     assertEquals("baz inner", exec_state.frame(0).evaluate("baz").value());
     assertEquals("baz outer", exec_state.frame(1).evaluate("baz").value());
     exec_state.frame(0).evaluate("w = 'w foo'");
-    exec_state.frame(0).evaluate("inner = 'inner foo'");
-    exec_state.frame(0).evaluate("outer = 'outer foo'");
-    exec_state.frame(0).evaluate("baz = 'baz inner foo'");
-    exec_state.frame(1).evaluate("baz = 'baz outer foo'");
+    exec_state.frame(0).evaluate("inner = 'inner foo'");  // no effect
+    exec_state.frame(0).evaluate("outer = 'outer foo'");  // has effect
+    exec_state.frame(0).evaluate("baz = 'baz inner foo'");  // no effect
+    exec_state.frame(1).evaluate("baz = 'baz outer foo'");  // has effect
     listened = true;
   } catch (e) {
     print(e);
     print(e.stack);
   }
 }
 
 Debug.setListener(listener);
 
 var outer = "outer";
 var baz = "baz outer";
 
 function foo() {
   var inner = "inner";
   var baz = "baz inner";
   var goo = "goo";
   var withw = { w: "w" };
   var withv = { v: "v" };
 
   with (withv) {
     var bar = function bar() {
-      assertEquals("goo foo", goo);
-      inner = "inner bar";  // this has no effect, when called from debug-eval
-      outer = "outer bar";  // this has no effect, when called from debug-eval
+      assertEquals("goo", goo);
+      inner = "inner bar";
+      outer = "outer bar";
       v = "v bar";
       return "bar return";
     };
   }
 
   with (withw) {
     debugger;
   }
 
-  assertEquals("inner foo", inner);
-  assertEquals("baz inner foo", baz);
+  assertEquals("inner bar", inner);
+  assertEquals("baz inner", baz);
   assertEquals("w foo", withw.w);
   assertEquals("v bar", withv.v);
 }
 
 foo();
 assertEquals("outer foo", outer);
 assertEquals("baz outer foo", baz);
 assertTrue(listened);
 Debug.setListener(null);