WebGLRenderer: Additional changes for reversed depth buffer

[WestLangley]

Description

Additional changes are required for WebGLRenderer to properly support a reversed depth buffer.

Shadow Bias - Either modify the shaders to accommodate a reversed depth buffer, or do nothing, and require the user to negate the bias at the app level.

I expect shadowNormalBias is OK as-is, but it would be good if someone can confirm that.

SSAO - With reversed depth buffer, shadows incorrectly appear inside the edge of the mesh.

Depth-Of-Field - TBD

Reproduction steps

n/a

Code

n/a

Live example

n/a

Screenshots

No response

Version

r180

Device

No response

Browser

No response

OS

No response

[Mugen87]

VSM is also broken with reversed depth buffers, see #31661. Besides, PCF shadows for point lights do not work as expected as well.