fix A-Frame text causing mirrored camera view on iOS 11.3

[machenmusik]

Changes Proposed:

save and configure extra values we need, then restore when we're done, so that using A-Frame text doesn't mirror camera view on iOS 11.3

Fixes:

save and restore flipY and frontFace also, TEXTURE_BINDING_2D

Checklist:

• [x] Tested on WebARonARCore
• [x] Tested on WebARonARKit
• [x] I've read CONTRIBUTING.md and signed the CLA (required)
• [x] This PR does not contain built changes in dist/\* (required)
• [x] This PR only contains one commit (required)

[judax]

Great job solving this problem @machenmusik !