DOF Far/Near Blur causes artifacts when glow is enabled

[sketchyfun]

Operating system or device - Godot version:
Windows 7 64bit
Godot 3.0 built from July 18th source (although I've seen this in earlier versions)
Running on a GeForce GTX 760

Issue description:
When you have both DOF Far Blur (or Near Blur) and Glow enabled, the glow texture becomes corrupted, as seen in the gif below:

Steps to reproduce:
Just enable DOF Far Blur and Glow at the same time

[kubecz3k]

for me on 4fe6b2a with those settings on, on linux and GTX1060 it looks better but also not good:

[ghost]

Just wondering, is glow_bicubic_upscale enabled? I've seen a similar issue with this option enabled.

[sketchyfun]

@kubecz3k this is a separate issue I think. The values need capping otherwise it wraps around and causes the strange colours. If you change the glow mode to Additive, it works, it's just the other modes that are broken at the moment

[sketchyfun]

@Noshyaar yes, but if I disable it, I don't get the glow effect at all (it used to work when I tested it many months ago)

[ghost]

@kubecz3k That's #9106 I think.

[vnen]

Likely fixed by f5277e3. Let us know if it's not the case.