Tests modified for IndexedDB
cc Renamed files (replace NNN-* with description).
cc Updated messages.json file.
Merge pull request #1289 from w3c/submission/sideshowbarker/file-rename

cc Renamed files (replace NNN-* with description).
modify test cases
Merge pull request #1250 from zhaozihao/zhaozihao/tests/IndexedDB

Tests modified for IndexedDB