Reduce window rectangles cap to 8

src/gpu/GrCaps.cpp

Index: src/gpu/GrCaps.cpp
diff --git a/src/gpu/GrCaps.cpp b/src/gpu/GrCaps.cpp
index 622c6855fae0ad93e29fd05c4fc6c62a0b65df45..9f92210ae8bce6db26ab211ccb1cb543e70260ef 100644
--- a/src/gpu/GrCaps.cpp
+++ b/src/gpu/GrCaps.cpp
@@ -141,6 +141,8 @@ void GrCaps::applyOptionsOverrides(const GrContextOptions& options) {
         fMaxTileSize = options.fMaxTileSizeOverride;
     }
     if (fMaxWindowRectangles > GrWindowRectangles::kMaxWindows) {
+        SkDebugf("WARNING: capping window rectangles at %i. HW advertises support for %i.\n",
+                 GrWindowRectangles::kMaxWindows, fMaxWindowRectangles);
         fMaxWindowRectangles = GrWindowRectangles::kMaxWindows;
     }
 }