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

test/mjsunit/es6/debug-blockscopes.js

 // Copyright 2011 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
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 //       from this software without specific prior written permission.
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 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // 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
 // The functions used for testing backtraces. They are at the top to make the
 // testing of source line/column easier.
 
 "use strict";
 
 // Get the Debug object exposed from the debug context global object.
 var Debug = debug.Debug;
 
 var test_name;
 var listener_delegate;
@@ skipping 479 matching lines @@
 EndTest();
 
 
 // Block scopes shadowing
 BeginTest("Block scopes shadowing 1");
 function shadowing_1() {
   let i = 0;
   {
     let i = 5;
     debugger;
+    assertEqualsUnlessOptimized(27, i, shadowing_1);
   }
   assertEquals(0, i);
+  debugger;
+  assertEqualsUnlessOptimized(27, i, shadowing_1);
 }
 
 listener_delegate = function (exec_state) {
-  assertEqualsUnlessOptimized(5, exec_state.frame(0).evaluate("i").value());
+  exec_state.frame(0).evaluate("i = 27");
 }
 shadowing_1();
 EndTest();
 
 
 // Block scopes shadowing
 BeginTest("Block scopes shadowing 2");
 function shadowing_2() {
   let i = 0;
   {
     let j = 5;
     debugger;
+    assertEqualsUnlessOptimized(27, j, shadowing_2);
   }
+  assertEqualsUnlessOptimized(0, i, shadowing_2);
 }
 
 listener_delegate = function (exec_state) {
-  assertEqualsUnlessOptimized(0, exec_state.frame(0).evaluate("i").value());
-  assertEqualsUnlessOptimized(5, exec_state.frame(0).evaluate("j").value());
+  exec_state.frame(0).evaluate("j = 27");
 }
 shadowing_2();
 EndTest();