Make GL_ANGLE_instanced_arrays enableable.

BUG=angleproject:1523

Change-Id: Id1dd5d0426c1b55bfd6cca8b0c8c73596080f2a9
Reviewed-on: https://chromium-review.googlesource.com/688101
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>
diff --git a/src/tests/gl_tests/WebGLCompatibilityTest.cpp b/src/tests/gl_tests/WebGLCompatibilityTest.cpp
index 4475a5d..0d098aa 100644
--- a/src/tests/gl_tests/WebGLCompatibilityTest.cpp
+++ b/src/tests/gl_tests/WebGLCompatibilityTest.cpp
@@ -672,6 +672,32 @@
     }
 }
 
+// Test enabling the GL_ANGLE_instanced_arrays extension
+TEST_P(WebGLCompatibilityTest, EnableInstancedArraysExtension)
+{
+    EXPECT_FALSE(extensionEnabled("GL_ANGLE_instanced_arrays"));
+
+    // This extensions become core in in ES3/WebGL2.
+    ANGLE_SKIP_TEST_IF(getClientMajorVersion() >= 3);
+
+    GLint divisor = 0;
+    glGetVertexAttribiv(0, GL_VERTEX_ATTRIB_ARRAY_DIVISOR, &divisor);
+    EXPECT_GL_ERROR(GL_INVALID_ENUM);
+
+    glVertexAttribDivisorANGLE(0, 1);
+    EXPECT_GL_ERROR(GL_INVALID_OPERATION);
+
+    if (extensionRequestable("GL_ANGLE_instanced_arrays"))
+    {
+        glRequestExtensionANGLE("GL_ANGLE_instanced_arrays");
+        EXPECT_GL_NO_ERROR();
+
+        glGetVertexAttribiv(0, GL_VERTEX_ATTRIB_ARRAY_DIVISOR, &divisor);
+        glVertexAttribDivisorANGLE(0, 1);
+        EXPECT_GL_NO_ERROR();
+    }
+}
+
 // Verify that the context generates the correct error when the framebuffer attachments are
 // different sizes
 TEST_P(WebGLCompatibilityTest, FramebufferAttachmentSizeMissmatch)