message: Test for clipping shader exceeding max varying vectors.
  Currently skipped as it will fail. Unskip when defect addressed.
diff: @@ -12,6 +12,9 @@ import {
  Target,
  System,
  TechniqueId,
  + TechniqueFlags,
  + ClippingType,
  + FeatureMode,
  SingularTechnique,
  ViewportQuadGeometry,
  DrawParams,
  @@ -75,4 +78,20 @@ describe("Technique tests", () => {
  expect(System.instance.techniques.compileShaders()).to.be.true;
  }
  });
  +
  + // Clipping planes add an extra varying vec4 which was causing surface shaders to exceed max varying vectors (capped at min guaranteed by spec, primarily because iOS).
  + // Verify this no longer occurs.
  + it.skip("should successfully compile surface shader with clipping planes", () => {
  + if (!WebGLTestContext.isInitialized)
  + return;
  +
  + const flags = new TechniqueFlags(true);
  + flags.clip.type = ClippingType.Planes;
  + flags.clip.numberOfPlanes = 6;
  + flags.featureMode = FeatureMode.Overrides;
  +
  + const tech = System.instance.techniques.getTechnique(TechniqueId.Surface);
  + const prog = tech.getShader(flags);
  + expect(prog.compile()).to.be.true;
  + });
  });
  