D3D: Fix incorrect instanced vertex offsets. The spec says that DrawElements is equivalent to the instanced call with an instance ID of zero. This patch fixes a bug in our VertexDataManager where we would sometimes ignore the attribute divisor for DrawElements, and stream the wrong amount of data/wrong start offset. BUG=angleproject:1213 TEST=dEQP-GLES3.functional.draw.draw_elements.* TEST=dEQP-GLES3.functional.draw.draw_range_elements.* TEST=dEQP-GLES3.functional.draw.random.* Change-Id: I1c430a14ab3be68a24e233e9cdd1e4fd88c920a0 Reviewed-on: https://chromium-review.googlesource.com/312062 Tryjob-Request: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>