[debugger] step on every assignment in a destructuring assignment.

R=caitpotter88@gmail.com, littledan@chromium.org
BUG=v8:811
LOG=N

Review URL: https://codereview.chromium.org/1533313002

Cr-Commit-Position: refs/heads/master@{#33000}

src/parsing/pattern-rewriter.cc

@@ -117,7 +117,7 @@ void Parser::PatternRewriter::VisitVariableProxy(VariableProxy* pattern) {
     Assignment* assignment = factory()->NewAssignment(
         Token::ASSIGN, pattern, value, pattern->position());
     block_->statements()->Add(
-        factory()->NewExpressionStatement(assignment, RelocInfo::kNoPosition),
+        factory()->NewExpressionStatement(assignment, pattern->position()),
         zone());
     return;
   }

test/mjsunit/harmony/debug-step-destructuring-assignment.js

+// 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 --harmony-destructuring-assignment
+// Flags: --harmony-destructuring-bind
+
+var exception = null;
+var Debug = debug.Debug;
+var break_count = 0;
+
+function listener(event, exec_state, event_data, data) {
+  if (event != Debug.DebugEvent.Break) return;
+  try {
+    var source = exec_state.frame(0).sourceLineText();
+    print(source);
+    assertTrue(source.indexOf(`// B${break_count++}`) > 0);
+    if (source.indexOf("assertEquals") > 0) {
+      exec_state.prepareStep(Debug.StepAction.StepNext);
+    } else {
+      exec_state.prepareStep(Debug.StepAction.StepIn);
+    }
+  } catch (e) {
+    exception = e;
+    print(e);
+  }
+};
+
+Debug.setListener(listener);
+
+function f() {
+  var a, b, c, d;
+  debugger;                                       // B0
+  [                                               // B1
+    a,                                            // B3
+    b,                                            // B4
+    c = 3                                         // B5
+  ] = [1, 2];                                     // B2
+  assertEquals({a:1,b:2,c:3}, {a, b, c});         // B6
+
+  [                                               // B7
+    a,                                            // B9
+    [
+      b,                                          // B10
+      c                                           // B11
+    ],
+    d                                             // B12
+  ] = [5, [6, 7], 8];                             // B8
+  assertEquals({a:5,b:6,c:7,d:8}, {a, b, c, d});  // B13
+
+  [                                               // B14
+    a,                                            // B16
+    b,                                            // B17
+    ...c                                          // B18
+  ] = [1, 2, 3, 4];                               // B15
+  assertEquals({a:1,b:2,c:[3,4]}, {a, b, c});     // B19
+
+  ({                                              // B20
+    a,                                            // B22
+    b,                                            // B23
+    c = 7                                         // B24
+  } = {a: 5, b: 6});                              // B21
+  assertEquals({a:5,b:6,c:7}, {a, b, c});         // B25
+
+  ({                                              // B26
+    a,                                            // B28
+    b = return1(),                                // B29
+    c = return1()                                 // B30
+  } = {a: 5, b: 6});                              // B27
+  assertEquals({a:5,b:6,c:1}, {a, b, c});         // B33
+
+  ({                                              // B34
+    x : a,                                        // B36
+    y : b,                                        // B37
+    z : c = 3                                     // B38
+  } = {x: 1, y: 2});                              // B35
+  assertEquals({a:1,b:2,c:3}, {a, b, c});         // B39
+}                                                 // B40
+
+function return1() {
+  return 1;                                       // B31
+}                                                 // B32
+
+f();
+Debug.setListener(null);                          // B41
+assertNull(exception);