deps: cherry-pick 09de996 from V8 upstream

deps/v8/include/v8-version.h

@@ -11,7 +11,7 @@
 #define V8_MAJOR_VERSION 5
 #define V8_MINOR_VERSION 6
 #define V8_BUILD_NUMBER 326
-#define V8_PATCH_LEVEL 56
+#define V8_PATCH_LEVEL 57
 
 // Use 1 for candidates and 0 otherwise.
 // (Boolean macro values are not supported by all preprocessors.)

deps/v8/src/parsing/parser-base.h

@@ -5008,7 +5008,7 @@ typename ParserBase<Impl>::StatementT ParserBase<Impl>::ParseSwitchStatement(
 
   {
     BlockState cases_block_state(zone(), &scope_state_);
-    cases_block_state.set_start_position(scanner()->location().beg_pos);
+    cases_block_state.set_start_position(switch_pos);
     cases_block_state.SetNonlinear();
     typename Types::Target target(this, switch_statement);
 

deps/v8/src/parsing/parser.cc

@@ -1729,6 +1729,10 @@ Statement* Parser::RewriteSwitchStatement(Expression* tag,
   Block* cases_block = factory()->NewBlock(NULL, 1, false, kNoSourcePosition);
   cases_block->statements()->Add(switch_statement, zone());
   cases_block->set_scope(scope);
+  DCHECK_IMPLIES(scope != nullptr,
+                 switch_statement->position() >= scope->start_position());
+  DCHECK_IMPLIES(scope != nullptr,
+                 switch_statement->position() < scope->end_position());
   switch_block->statements()->Add(cases_block, zone());
   return switch_block;
 }

deps/v8/test/debugger/regress/regress-6085.js

@@ -0,0 +1,49 @@
+// Copyright 2017 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.
+
+function* serialize() {
+  debugger;
+  switch (0) {
+    case 0:
+      let x = 1;
+      return x;  // Check scopes
+  }
+}
+
+let exception = null;
+let step_count = 0;
+let scopes_checked = false;
+
+function listener(event, exec_state, event_data, data) {
+  if (event != Debug.DebugEvent.Break) return;
+  try {
+    if (exec_state.frame().sourceLineText().includes("Check scopes")) {
+      let expected = [ debug.ScopeType.Block,
+                       debug.ScopeType.Local,
+                       debug.ScopeType.Script,
+                       debug.ScopeType.Global ];
+      for (let i = 0; i < exec_state.frame().scopeCount(); i++) {
+        assertEquals(expected[i], exec_state.frame().scope(i).scopeType());
+      }
+      scopes_checked = true;
+    }
+    if (step_count++ < 3) exec_state.prepareStep(Debug.StepAction.StepNext);
+  } catch (e) {
+    exception = e;
+    print(e, e.stack);
+  }
+}
+
+
+
+let Debug = debug.Debug;
+Debug.setListener(listener);
+
+let gen = serialize();
+gen.next();
+
+Debug.setListener(null);
+assertNull(exception);
+assertEquals(4, step_count);
+assertTrue(scopes_checked);