[Engine] allow --enable-asserts flag to be passed to dart vm in profile mode.

shell/common/switches.cc

@@ -65,6 +65,7 @@ static const std::string kAllowedDartFlags[] = {
     "--null_assertions",
     "--strict_null_safety_checks",
     "--max_subtype_cache_entries",
+    "--enable-asserts",
 };
 // clang-format on
 

shell/common/switches_unittests.cc

@@ -123,6 +123,16 @@ TEST(SwitchesTest, NoEnableImpeller) {
   }
 }
 
+#if !FLUTTER_RELEASE
+TEST(SwitchesTest, EnableAsserts) {
+  fml::CommandLine command_line = fml::CommandLineFromInitializerList(
+      {"command", "--dart-flags=--enable-asserts"});
+  Settings settings = SettingsFromCommandLine(command_line);
+  ASSERT_EQ(settings.dart_flags.size(), 1ul);
+  EXPECT_EQ(settings.dart_flags[0], "--enable-asserts");
+}
+#endif
+
 }  // namespace testing
 }  // namespace flutter