Status bar mode label inconsistent with nested modes

[peterflynn]

1. Open an HTML file containing inline JS in a script block
2. Put cursor inside the script block
3. Switch to a different file
4. Switch back

Result:
1-2: mode says "html"
4: mode says "javascript"

Expected:
Status bar consistently shows outermost mode of file ("html" in this case).

[peterflynn]

Problem is that it's using the cursor-location-specific API Editor.getModeForSelection(). We should add a method for getting the top-level (file-wide) mode and use that instead.

Note that this will make #1826 a little more obvious though, since HTML files will start using the label "htmlmixed" if we're accurately reporting the outermode.

[njx]

See comments on #1826 - moving to Sprint 16, could consider removing this from the status bar for the next Edge Code drop if we don't want to fix this yet.

[pthiess]

Assigned to Randy.

[RaymondLim]

FBNC to @peterflynn

[peterflynn]

Confirmed fixed