Fix Web IDE tree not updating modified status

What does this MR do?

This MR fixes issues with the file in the file tree's state being out of sync.

Screenshots

Before	After
20191016_ide_fix_before	20191016_ide_fix_after

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

References

• #29881 (closed)