GLES1: glClientActiveTexture

+ adds query for GL_MAX_TEXTURE_UNITS

BUG=angleproject:2306

Change-Id: Ie89fa6a067551170856bf0f7e6d7b4452b3da132
Reviewed-on: https://chromium-review.googlesource.com/984894
Commit-Queue: Lingfeng Yang <lfy@google.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/validationES2.cpp b/src/libANGLE/validationES2.cpp
index 8146679..ab448a6 100644
--- a/src/libANGLE/validationES2.cpp
+++ b/src/libANGLE/validationES2.cpp
@@ -4340,7 +4340,7 @@
     if (texture < GL_TEXTURE0 ||
         texture > GL_TEXTURE0 + context->getCaps().maxCombinedTextureImageUnits - 1)
     {
-        context->handleError(InvalidEnum());
+        ANGLE_VALIDATION_ERR(context, InvalidEnum(), InvalidCombinedImageUnit);
         return false;
     }