Fix iPhone6 Programs test.

We shouldn't need to disable shader derivatives on iOS, so this
should fix the assert in this test.

Change-Id: Icb4fa0af3ad5822e1509f3c9857a8d52c6e85762
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/418578
Reviewed-by: Chris Dalton <csmartdalton@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index 421585f..a9e3e10 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -4150,9 +4150,11 @@
     }
 
     // http://crbug.com/1197152
+#ifndef SK_BUILD_FOR_IOS
     if (ctxInfo.renderer() == GrGLRenderer::kPowerVRRogue) {
         fShaderCaps->fShaderDerivativeSupport = false;
     }
+#endif
 }
 
 void GrGLCaps::onApplyOptionsOverrides(const GrContextOptions& options) {