Java support disabled in diff editor for staged files

See: https://github.com/Microsoft/vscode/issues/34034

It is the case in some other vscode language extensions that one can go to definitions directly from the right hand pane of the diff editor (ie, from the pane that represents the current version of the file). This is great utility when looking at diffs, reviewing changes, etc.

This is currently the case for TS/JS and used to be the case for Go (there was some sort of regression). It would be great if Java supported this.

Environment

• Operating System: Mac OS X, 10.11.6, Darwin x64 15.6.0
• JDK version: 1.8.0_92
• Visual Studio Code version: Code 1.16.0 (787b31c0474e6165390b5a5989c9619e3e16f953, 2017-09-06T16:12:42.401Z)
• Java extension version: 0.9.0

Steps To Reproduce

1. Open a diff editor where one of the panes is the current version of the file, e.g., by going to the source control view and (in the case of git) clicking on one of the diffs for the staged or working tree changes.
2. Attempt to go to a definition.

Current Result

A message indicating that the definition was not found.

Expected Result

Go to Definition and other tooling (symbols, etc) should work in the pane that represents the current version of the file.

Start by reproducing the steps in the VS Code source control view and diff editor with a staged or working-tree Java change. Trace how Go to Definition and symbols are handled in the current-version pane, then verify that these tools work there without the definition-not-found message.