Add support for querying GL_MAX_VARYING_COMPONENTS.
Add support for querying GL_MAX_VARYING_COMPONENTS.

BUG=angle:645

Change-Id: I2e33798bd7fe6cabb1237224aeb9e59cdf03f73c
Reviewed-on: https://chromium-review.googlesource.com/198836
Reviewed-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@chromium.org>
Reviewed-by: Shannon Woods <0f3694938fd5703bd548127ee497e4d604509bef@chromium.org>
Tested-by: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>

ghostoy/angle,ecoal95/angle,mrobinson/rust-angle,jgcaaprom/android_external_chromium_org_third_party_angle,mikolalysenko/angle,domokit/waterfall,bsergean/angle,ecoal95/angle,xin3liang/platform_external_chromium_org_third_party_angle,mikolalysenko/angle,xin3liang/platform_external_chromium_org_third_party_angle,csa7mdm/angle,ppy/angle,larsbergstrom/angle,MSOpenTech/angle,mlfarrell/angle,csa7mdm/angle,MIPS/external-chromium_org-third_party-angle,geekboxzone/lollipop_external_chromium_org_third_party_angle,mybios/angle,nandhanurrevanth/angle,ppy/angle,crezefire/angle,larsbergstrom/angle,ecoal95/angle,bsergean/angle,android-ia/platform_external_chromium_org_third_party_angle,nandhanurrevanth/angle,MIPS/external-chromium_org-third_party-angle,jgcaaprom/android_external_chromium_org_third_party_angle,nandhanurrevanth/angle,ppy/angle,nandhanurrevanth/angle,crezefire/angle,geekboxzone/lollipop_external_chromium_org_third_party_angle,mybios/angle,mlfarrell/angle,larsbergstrom/angle,csa7mdm/angle,domokit/waterfall,larsbergstrom/angle,jgcaaprom/android_external_chromium_org_third_party_angle,mlfarrell/angle,MSOpenTech/angle,mlfarrell/angle,mrobinson/rust-angle,bsergean/angle,MSOpenTech/angle,ppy/angle,mrobinson/rust-angle,mybios/angle,mikolalysenko/angle,vvuk/angle,android-ia/platform_external_chromium_org_third_party_angle,mrobinson/rust-angle,vvuk/angle,vvuk/angle,MSOpenTech/angle,mikolalysenko/angle,MIPS/external-chromium_org-third_party-angle,crezefire/angle,xin3liang/platform_external_chromium_org_third_party_angle,vvuk/angle,MIPS/external-chromium_org-third_party-angle,crezefire/angle,xin3liang/platform_external_chromium_org_third_party_angle,android-ia/platform_external_chromium_org_third_party_angle,jgcaaprom/android_external_chromium_org_third_party_angle,mrobinson/rust-angle,bsergean/angle,geekboxzone/lollipop_external_chromium_org_third_party_angle,ecoal95/angle,android-ia/platform_external_chromium_org_third_party_angle,ecoal95/angle,ghostoy/angle,geekboxzone/lollipop_external_chromium_org_third_party_angle,mybios/angle,csa7mdm/angle,ghostoy/angle,ghostoy/angle