Fix developer error when zooming creates an invalid frustum. Also fix crash when attempting to normalize the zero vector during translation in 2D.
Merge branch 'master' into cameraZoom2D

Conflicts:
	CHANGES.md
Add test for clamping zoom in 2D.
Merge branch 'master' into cameraZoom2D
Rewrite combine to change defaults and get rid of array allocations.
update CHANGES.
Merge pull request #1437 from AnalyticalGraphicsInc/cameraZoom2D

Fix DeveloperError when zooming in 2D
Include response headers in RequestErrorEvent.
Move @private to the end of the jsdoc
Fix test failures caused by incomplete stubbing of XMLHttpRequest.
Update CHANGES.md.
Don't used defined(window) because window is not declared.

In fact, avoid `window` entirely and just check for the existence of a
global `performance` property.

This fixes issue #1457.
Merge pull request #1458 from AnalyticalGraphicsInc/avoidWindow

Don't used defined(window) because window is not declared.
Updates from review.
Merge pull request #1451 from AnalyticalGraphicsInc/combine

Rewrite combine to change defaults and get rid of array allocations.
Merge pull request #1455 from AnalyticalGraphicsInc/responseHeaders

Include response headers in RequestErrorEvent.
Replace truthy statement with defined.
Merge remote-tracking branch 'origin/master' into dynamicScene-refactor