adjust gm bounds for better content fit

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1876753003

TBR=djsollen

Review URL: https://codereview.chromium.org/1876753003
diff --git a/gm/tilemodes.cpp b/gm/tilemodes.cpp
index b7f0d45..bd2dcfe 100644
--- a/gm/tilemodes.cpp
+++ b/gm/tilemodes.cpp
@@ -194,7 +194,7 @@
         return fName;
     }
 
-    SkISize onISize() override { return SkISize::Make(880, 560); }
+    SkISize onISize() override { return SkISize::Make(650, 610); }
 
     void onDraw(SkCanvas* canvas) override {
         canvas->scale(SkIntToScalar(3)/2, SkIntToScalar(3)/2);