[log][api] Fix GCC 4.9 build failure

GCC 4.9 used on some Node.js CI machines complains when the control
reaches the end of a non-void function and no return is encountered.

R=bmeurer@google.com, ofrobots@google.com, yangguo@google.com

Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: I5af0192cb187eccbf34dbb60ff3ac2e4774af803
Reviewed-on: https://chromium-review.googlesource.com/1105619Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53861}

src/api.cc

@@ -10217,6 +10217,10 @@ const char* CodeEvent::GetCodeEventTypeName(CodeEventType code_event_type) {
       CODE_EVENTS_LIST(V)
 #undef V
   }
+  // The execution should never pass here
+  UNREACHABLE();
+  // NOTE(mmarchini): Workaround to fix a compiler failure on GCC 4.9
+  return "Unknown";
 }
 
 CodeEventHandler::CodeEventHandler(Isolate* isolate) {

src/log.cc

@@ -59,6 +59,10 @@ static v8::CodeEventType GetCodeEventTypeForTag(
       TAGS_LIST(V)
 #undef V
   }
+  // The execution should never pass here
+  UNREACHABLE();
+  // NOTE(mmarchini): Workaround to fix a compiler failure on GCC 4.9
+  return v8::CodeEventType::kUnknownType;
 }
 #define CALL_CODE_EVENT_HANDLER(Call) \
   if (listener_) {                    \