Memory leak when OpenGLCore, GLES3 or GLES2 is set as the default graphics API in Windows.

Repro steps:
1. Open EmptyScene from attached project or create new empty project.
2. Open up task manager (Ctrl+Shift+Esc) and observe Unity's memory usage.
3. Make sure the graphics API in player settings is set to OpenGLCore, GLES3 or GLES2.
4. Restore down and maximize Unity's editor window (the middle button between minimize and close)
5. Observe the memory leak in the task manager.

Expected outcome: no memory leak.

Notes:
- does not repro on OSX; seems to be a Win-only issue.
- issue appears in trunk (5.5.0a1)
- does not repro in 5.3.1f1 or 5.4.0b15; 5.5-specific.
- closing the scene view seems to alleviate the issue.
- toggling the effects preview button in the scene view seems to speed up the memory leak.