deps: cherry-pick 50f7455 from upstream V8

Original commit message:

    [inspector] added Runtime.globalLexicalScopeNames method

    The method returns names for all available top-level scope variables
    in giving context.

    R=dgozman@chromium.org,jgruber@chromium.org

    Bug: chromium:681333
    Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
    Change-Id: I2d0b600e1afbfef9087f53ea9c26abe1e112047c
    Reviewed-on: https://chromium-review.googlesource.com/719409
    Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
    Reviewed-by: Yang Guo <yangguo@chromium.org>
    Reviewed-by: Jakob Gruber <jgruber@chromium.org>
    Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#48618}

Refs: https://github.com/v8/v8/commit/50f7455cd973864fe70cc04f97146f725b7c3e54

PR-URL: https://github.com/nodejs/node/pull/16591
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

3 files changed, 35 insertions, 0 deletions

diff --git a/deps/v8/src/inspector/js_protocol.json b/deps/v8/src/inspector/js_protocol.json
index df7db67cdb..2d493e5b74 100644
--- a/deps/v8/src/inspector/js_protocol.json
+++ b/deps/v8/src/inspector/js_protocol.json
@@ -355,6 +355,17 @@
                     { "name": "objects", "$ref": "RemoteObject", "description": "Array with objects." }
                 ],
                 "experimental": true
+            },
+            {
+                "name": "globalLexicalScopeNames",
+                "parameters": [
+                    { "name": "executionContextId", "$ref": "ExecutionContextId", "optional": true, "description": "Specifies in which execution context to lookup global scope variables." }
+                ],
+                "returns": [
+                    { "name": "names", "type": "array", "items": { "type": "string" } }
+                ],
+                "description": "Returns all let, const and class variables from global scope.",
+                "experimental": true
             }
         ],
         "events": [
diff --git a/deps/v8/src/inspector/v8-runtime-agent-impl.cc b/deps/v8/src/inspector/v8-runtime-agent-impl.cc
index 8ecfbc5791..22d48e23bf 100644
--- a/deps/v8/src/inspector/v8-runtime-agent-impl.cc
+++ b/deps/v8/src/inspector/v8-runtime-agent-impl.cc
@@ -586,6 +586,27 @@ Response V8RuntimeAgentImpl::queryObjects(
       resultArray, scope.objectGroupName(), false, false, objects);
 }
 
+Response V8RuntimeAgentImpl::globalLexicalScopeNames(
+    Maybe<int> executionContextId,
+    std::unique_ptr<protocol::Array<String16>>* outNames) {
+  int contextId = 0;
+  Response response = ensureContext(m_inspector, m_session->contextGroupId(),
+                                    std::move(executionContextId), &contextId);
+  if (!response.isSuccess()) return response;
+
+  InjectedScript::ContextScope scope(m_session, contextId);
+  response = scope.initialize();
+  if (!response.isSuccess()) return response;
+
+  v8::PersistentValueVector<v8::String> names(m_inspector->isolate());
+  v8::debug::GlobalLexicalScopeNames(scope.context(), &names);
+  *outNames = protocol::Array<String16>::create();
+  for (size_t i = 0; i < names.Size(); ++i) {
+    (*outNames)->addItem(toProtocolString(names.Get(i)));
+  }
+  return Response::OK();
+}
+
 void V8RuntimeAgentImpl::restore() {
   if (!m_state->booleanProperty(V8RuntimeAgentImplState::runtimeEnabled, false))
     return;
diff --git a/deps/v8/src/inspector/v8-runtime-agent-impl.h b/deps/v8/src/inspector/v8-runtime-agent-impl.h
index 1d5067b560..cc63b697c9 100644
--- a/deps/v8/src/inspector/v8-runtime-agent-impl.h
+++ b/deps/v8/src/inspector/v8-runtime-agent-impl.h
@@ -101,6 +101,9 @@ class V8RuntimeAgentImpl : public protocol::Runtime::Backend {
   Response queryObjects(
       const String16& prototypeObjectId,
       std::unique_ptr<protocol::Runtime::RemoteObject>* objects) override;
+  Response globalLexicalScopeNames(
+      Maybe<int> executionContextId,
+      std::unique_ptr<protocol::Array<String16>>* outNames) override;
 
   void reset();
   void reportExecutionContextCreated(InspectedContext*);