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/Context.cpp b/src/libANGLE/Context.cpp
index cba6b77..64a0463 100644
--- a/src/libANGLE/Context.cpp
+++ b/src/libANGLE/Context.cpp
@@ -1602,6 +1602,10 @@
         case GL_MAX_GEOMETRY_SHADER_STORAGE_BLOCKS_EXT:
             *params = mCaps.maxGeometryShaderStorageBlocks;
             break;
+        // GLES1 emulation: Caps queries
+        case GL_MAX_TEXTURE_UNITS:
+            *params = mCaps.maxMultitextureUnits;
+            break;
         default:
             handleError(mGLState.getIntegerv(this, pname, params));
             break;
@@ -6385,6 +6389,14 @@
                 *type      = GL_FLOAT;
                 *numParams = 1;
                 return true;
+            case GL_MAX_TEXTURE_UNITS:
+                *type      = GL_INT;
+                *numParams = 1;
+                return true;
+            case GL_CLIENT_ACTIVE_TEXTURE:
+                *type      = GL_INT;
+                *numParams = 1;
+                return true;
         }
     }