Introduce 'replMode' flag for Runtime.evaluate

This CL adds a boolean flag to Runtime.evaluate that allows REPL
mode to be enabled. REPL mode hasn't landed in V8 yet, and the internal
API for it is still in flux.

R=yangguo@chromium.org

Bug: chromium:1004193
Change-Id: I281285e225d3fd2dd4175f3dd967d6562459a203
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1866510Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64470}

include/js_protocol.pdl

@@ -1257,6 +1257,8 @@ domain Runtime
       experimental optional TimeDelta timeout
       # Disable breakpoints during execution.
       experimental optional boolean disableBreaks
+      # Reserved flag for future REPL mode support. Setting this flag has currently no effect.
+      experimental optional boolean replMode
     returns
       # Evaluation result.
       RemoteObject result

src/inspector/v8-runtime-agent-impl.cc

@@ -235,7 +235,7 @@ void V8RuntimeAgentImpl::evaluate(
     Maybe<int> executionContextId, Maybe<bool> returnByValue,
     Maybe<bool> generatePreview, Maybe<bool> userGesture,
     Maybe<bool> awaitPromise, Maybe<bool> throwOnSideEffect,
-    Maybe<double> timeout, Maybe<bool> disableBreaks,
+    Maybe<double> timeout, Maybe<bool> disableBreaks, Maybe<bool> replMode,
     std::unique_ptr<EvaluateCallback> callback) {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"),
                "EvaluateScript");

src/inspector/v8-runtime-agent-impl.h

@@ -68,6 +68,7 @@ class V8RuntimeAgentImpl : public protocol::Runtime::Backend {
                 Maybe<bool> generatePreview, Maybe<bool> userGesture,
                 Maybe<bool> awaitPromise, Maybe<bool> throwOnSideEffect,
                 Maybe<double> timeout, Maybe<bool> disableBreaks,
+                Maybe<bool> replMode,
                 std::unique_ptr<EvaluateCallback>) override;
   void awaitPromise(const String16& promiseObjectId, Maybe<bool> returnByValue,
                     Maybe<bool> generatePreview,