Only enable SRGB write control on desktop GL when SRGB is supported.

src/gpu/gl/GrGLCaps.cpp

Index: src/gpu/gl/GrGLCaps.cpp
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index 9870a92c146343bcb9805b209e7714369fcd22ad..85be57a166f67f07a1c229e34fa6cc3e267f67b8 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -1468,7 +1468,9 @@ void GrGLCaps::initConfigTable(const GrGLContextInfo& ctxInfo, const GrGLInterfa
             }
         }
         // All the above srgb extensions support toggling srgb writes
-        fSRGBWriteControl = true;
+        if (fSRGBSupport) {
+            fSRGBWriteControl = true;
+        }
     } else {
         // See https://bug.skia.org/4148 for PowerVR issue.
         fSRGBSupport = kPowerVRRogue_GrGLRenderer != ctxInfo.renderer() &&