Fixed typos in observatory_sources and folder name

TBR=johnmccutchan@google.com

Review URL: https://codereview.chromium.org/2210103002 .
diff --git a/runtime/observatory/observatory_sources.gypi b/runtime/observatory/observatory_sources.gypi
index b675905..adf1c26 100644
--- a/runtime/observatory/observatory_sources.gypi
+++ b/runtime/observatory/observatory_sources.gypi
@@ -193,7 +193,7 @@
     'lib/src/mocks/objects/target.dart',
     'lib/src/mocks/objects/vm.dart',
     'lib/src/mocks/repositories/crash_dump.dart',
-    'lib/src/mocks/repositories/flags.dart',
+    'lib/src/mocks/repositories/flag.dart',
     'lib/src/mocks/repositories/script.dart',
     'lib/src/mocks/repositories/notification.dart',
     'lib/src/mocks/repositories/target.dart',
diff --git a/runtime/observatory/tests/observatory_ui/flag-list/element_test.dart b/runtime/observatory/tests/observatory_ui/flag_list/element_test.dart
similarity index 100%
rename from runtime/observatory/tests/observatory_ui/flag-list/element_test.dart
rename to runtime/observatory/tests/observatory_ui/flag_list/element_test.dart
diff --git a/runtime/observatory/tests/observatory_ui/flag-list/element_test.html b/runtime/observatory/tests/observatory_ui/flag_list/element_test.html
similarity index 100%
rename from runtime/observatory/tests/observatory_ui/flag-list/element_test.html
rename to runtime/observatory/tests/observatory_ui/flag_list/element_test.html