ANGLETest: swap after resizing the window, before running the test.
ANGLETest: swap after resizing the window, before running the test.

This allows the test code to assume that the framebuffer size is equal
to the window size.

BUG=angleproject:1050

Change-Id: Ia4928d7a1d6cddb1ae330846bb44576db6a37533
Reviewed-on: https://chromium-review.googlesource.com/286253
Reviewed-by: Kenneth Russell <1ebccd90c2bc76de65b6f830f2128a91ed69fdfb@chromium.org>
Reviewed-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>
Tested-by: Corentin Wallez <470c533e86f4f848c98c7e11fffc2d043494a401@chromium.org>

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