Remove paging from the WebGL backend

[dsmilkov]

Paging has been the source of various problems, so we've decided to remove it. Instead we will warn the user when the memory usage in WebGL is above a dynamically decided threshold.

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This change is 

[nsthorat]

Reviewed 5 of 5 files at r1.
Reviewable status: complete! 1 of 1 approvals obtained (waiting on @dsmilkov and @nsthorat)

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src/kernels/backend_webgl.ts, line 181 at r1 (raw file):

// Empirically determined constant used to decide the number of MB on GPU
// before we warn about high memory use. The MB are this constant * screen area
// * dpi / 1024.

woops, realized I wrote this comment.. should be over another 1024, my bad

[dsmilkov]

Reviewable status: complete! 1 of 1 approvals obtained

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src/kernels/backend_webgl.ts, line 181 at r1 (raw file):

Previously, nsthorat (Nikhil Thorat) wrote…

woops, realized I wrote this comment.. should be over another 1024, my bad

Done.