Change offsets in MultiDrawElements* entrypoints to match glMultiDrawElements

This patch changes arguments for MultiDrawElements and
MultiDrawElementsInstanced from from GLsizei *offsets to
const* GLvoid* indices.

Bug: chromium:890539

Change-Id: I2124cf2daeaa6af0f889f3c46aa2b8c77be200a6
Reviewed-on: https://chromium-review.googlesource.com/c/1352591
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
diff --git a/src/libANGLE/validationES3.cpp b/src/libANGLE/validationES3.cpp
index b499f1f..8fe7199 100644
--- a/src/libANGLE/validationES3.cpp
+++ b/src/libANGLE/validationES3.cpp
@@ -3153,7 +3153,7 @@
                                              PrimitiveMode mode,
                                              const GLsizei *counts,
                                              GLenum type,
-                                             const GLsizei *offsets,
+                                             const GLvoid *const *indices,
                                              const GLsizei *instanceCounts,
                                              GLsizei drawcount)
 {
@@ -3176,9 +3176,8 @@
     }
     for (GLsizei drawID = 0; drawID < drawcount; ++drawID)
     {
-        const void *indices = reinterpret_cast<void *>(static_cast<long>(offsets[drawID]));
-        if (!ValidateDrawElementsInstancedCommon(context, mode, counts[drawID], type, indices,
-                                                 instanceCounts[drawID]))
+        if (!ValidateDrawElementsInstancedCommon(context, mode, counts[drawID], type,
+                                                 indices[drawID], instanceCounts[drawID]))
         {
             return false;
         }