Implement drawRangeElements in RendererGL.
Implement drawRangeElements in RendererGL.

BUG=angleproject:1136

Change-Id: I8b84b845da09f60bfd5e8f400da47d759f0d8f1a
Reviewed-on: https://chromium-review.googlesource.com/295234
Reviewed-by: Corentin Wallez <470c533e86f4f848c98c7e11fffc2d043494a401@chromium.org>
Reviewed-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>
Tested-by: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>

mlfarrell/angle,mybios/angle,vvuk/angle,mikolalysenko/angle,ecoal95/angle,mikolalysenko/angle,csa7mdm/angle,crezefire/angle,mybios/angle,MSOpenTech/angle,ecoal95/angle,mlfarrell/angle,mikolalysenko/angle,vvuk/angle,crezefire/angle,mybios/angle,domokit/waterfall,mlfarrell/angle,domokit/waterfall,ecoal95/angle,ppy/angle,mlfarrell/angle,vvuk/angle,csa7mdm/angle,csa7mdm/angle,ecoal95/angle,csa7mdm/angle,mybios/angle,ecoal95/angle,MSOpenTech/angle,mikolalysenko/angle,crezefire/angle,ppy/angle,MSOpenTech/angle,ppy/angle,ppy/angle,MSOpenTech/angle,crezefire/angle,vvuk/angle