Cache MAX_TEXTURE_SIZE

[annxingyuan]

This PR addresses the issue tensorflow/tfjs#786 by caching the value of MAX_TEXTURE_SIZE within the function that queries the WebGL context.

BUG

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[nsthorat]

Reviewed 1 of 1 files at r1.
Reviewable status: complete! 2 of 1 approvals obtained (waiting on @annxingyuan, @nsthorat, and @dsmilkov)

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src/environment_util.ts, line 118 at r1 (raw file):

}

export const getWebGLMaxTextureSize = (() => {

no need to do this with a closure you can let the MAX_TEXTURE_SIZE live at the top level

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src/environment_util.ts, line 122 at r1 (raw file):

  // unit tests and we don't want to constantly query the WebGLContext for
  // MAX_TEXTURE_SIZE.
  let MAX_TEXTURE_SIZE: number = null;

for consistency with other places we do this don’t set it to null just leave it not defined

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src/environment_util.ts, line 124 at r1 (raw file):

  let MAX_TEXTURE_SIZE: number = null;
  return (webGLVersion: number, isBrowser: boolean): number => {
    if (MAX_TEXTURE_SIZE === null) {

prefer double equals over triple equals for null checks. double equals null also checks for undefined