fix path to codemirror-assets.html
fix path to codemirror-assets.html

Bug: Issue 9060
Change-Id: I7c3604ace0e013de8b5ef3e018299f6755e3dcf4

GerritCodeReview/plugins_codemirror-editor,GerritCodeReview/plugins_codemirror-editor,GerritCodeReview/plugins_codemirror-editor