[es6] support AssignmentPattern as LHS in for-in/of loops

test/cctest/test-parsing.cc

Index: test/cctest/test-parsing.cc
diff --git a/test/cctest/test-parsing.cc b/test/cctest/test-parsing.cc
index 942c5be02a6724efe810f52b05dc4c83b2331579..ff996bb91e1dc66716188e78c5e5f0ef4fe16d68 100644
--- a/test/cctest/test-parsing.cc
+++ b/test/cctest/test-parsing.cc
@@ -6830,6 +6830,21 @@ TEST(DestructuringAssignmentPositiveTests) {
       {"var x, y, z; for (x of ", " = {});"},
       {NULL, NULL}};
 
+  const char* mixed_assignments_context_data[][2] = {
+      {"'use strict'; let x, y, z; (", " = z = {});"},
+      {"var x, y, z; (", " = z = {});"},
+      {"'use strict'; let x, y, z; (x = ", " = z = {});"},
+      {"var x, y, z; (x = ", " = z = {});"},
+      {"'use strict'; let x, y, z; for (x in ", " = z = {});"},
+      {"'use strict'; let x, y, z; for (x in x = ", " = z = {});"},
+      {"'use strict'; let x, y, z; for (x of ", " = z = {});"},
+      {"'use strict'; let x, y, z; for (x of x = ", " = z = {});"},
+      {"var x, y, z; for (x in ", " = z = {});"},
+      {"var x, y, z; for (x in x = ", " = z = {});"},
+      {"var x, y, z; for (x of ", " = z = {});"},
+      {"var x, y, z; for (x of x = ", " = z = {});"},
+  };
+
   // clang-format off
   const char* data[] = {
     "x",
@@ -6945,8 +6960,8 @@ TEST(DestructuringAssignmentPositiveTests) {
     "[...x]",
     "[x,y,...z]",
     "[x,,...z]",
-    "{ x: y } = z",
-    "[x, y] = z",
+    "{ x: y }",
+    "[x, y]",
     "{ x: y } = { z }",
     "[x, y] = { z }",
     "{ x: y } = [ z ]",
@@ -6966,6 +6981,9 @@ TEST(DestructuringAssignmentPositiveTests) {
   RunParserSyncTest(context_data, data, kSuccess, NULL, 0, always_flags,
                     arraysize(always_flags));
 
+  RunParserSyncTest(mixed_assignments_context_data, data, kSuccess, NULL, 0,
+                    always_flags, arraysize(always_flags));
+
   const char* empty_context_data[][2] = {
       {"'use strict';", ""}, {"", ""}, {NULL, NULL}};