Bug fixes from the cygnus app.
Fix `Context.setThrowOnWebGLError`

Modify `wrapGL` so that instead of simply copying properties, it creates read/write ES5 properties.

Fixes #1215
Merge pull request #1216 from AnalyticalGraphicsInc/issue1215

Fix `Context.setThrowOnWebGLError`
Fixes an index out of bounds WebGL error when the count argument to glDrawElements is zero.
Merge pull request #1217 from AnalyticalGraphicsInc/outOfBoundsError

Fix PolylineCollection WebGL warning
Merge pull request #1214 from AnalyticalGraphicsInc/bugFixes

Bug Fixes
Merge branch 'master' into balloon