Update git submodules
Update git submodules

* Update plugins/codemirror-editor from branch 'master'
  to 767e6bfc028f438b4a1234ad6179aaba78a8b11e
  - Compatibility fix for Polymer 2
    
    Polymer 2 uses shadow dom. Before the fix all styles were loaded as a
    document-level styles. To load styles inside correct element this fix
    logically separates plugin in 2 parts: gr-editor and codemirror-element.
    The codemirror-element is a wrapper for codemirror and it incapsulates all
    styles and scripts inside the element. gr-editor connects codemirror-element
    with gerrit - it dynamically loads codemirror-element, set correct
    options and adds event listeners.
    Also, codemirror doesn't work with shadydom correctly. Because of it,
    there 2 versions of codemirror-element - one is for shadowdom and antoher one
    is for shadydom.
    
    Bug: Issue 11143
    Change-Id: I304cc73df1ea9a5c59fe295fe50c817ed266ffc2
    
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