Consolidated WebGL fixes into a single fix [skip ci]

CHANGES.md

@@ -16,14 +16,7 @@
 - Fixed artifact for skinned model when log depth is enabled. [#6447](https://github.com/CesiumGS/cesium/issues/6447)
 - Fixed a bug where certain rhumb arc polylines would lead to a crash. [#8787](https://github.com/CesiumGS/cesium/pull/8787)
 - Fixed handling of Label's backgroundColor and backgroundPadding option [#8949](https://github.com/CesiumGS/cesium/8949)
-- Fixed log depth artifacts when running CesiumJS in a WebGL2 context. [#8969](https://github.com/CesiumGS/cesium/pull/8969)
-- Fixed a bug where the camera goes through the geometry instead of stopping in front of it in WebGL 2. [#747](https://github.com/CesiumGS/cesium/issues/797#issuecomment-645660881)
-- Fixed a bug where silhouette postprocess doesn't work in WebGL 2. [#7952](https://github.com/CesiumGS/cesium/issues/7952)
-- Fixed an error of applying clip planes to globe when enabling WebGL 2.0 [#7712](https://github.com/CesiumGS/cesium/issues/7712)
-- Fixed a bug where half-float texture doesn't have correct WebGL 2.0 parameter [#8975](https://github.com/CesiumGS/cesium/pull/8975)
-- Fixed a bug where the label's text is not anti-aliased when enabling WebGL 2.0 [#797](https://github.com/CesiumGS/cesium/issues/797#issuecomment-646884821)
-- Fixed a bug where polylines get squashed when zooming when enabling WebGL 2.0 [#797](https://github.com/CesiumGS/cesium/issues/797#issuecomment-646918076)
-- Fixed a bug where contour lines are thinner when enabling WebGL 2.0 [#797](https://github.com/CesiumGS/cesium/issues/797#issuecomment-646920630)
+- Fixed several bugs when rendering CesiumJS in a WebG 2 context. [#797](https://github.com/CesiumGS/cesium/issues/797)
 
 ### 1.70.1 - 2020-06-10