Cleanup: Get rid of make_isize() function from gm.h.

This helper function is not necessary.

The same thing can be achieved by using SkISize::Make() provided by
SkTSize API.

BUG=skia:2645
TEST=make dm && out/Debug/dm
R=robertphillips@google.com, reed@google.com

Author: tfarina@chromium.org

Review URL: https://codereview.chromium.org/326523002
diff --git a/gm/beziereffects.cpp b/gm/beziereffects.cpp
index 6a9e65b..9252a58 100644
--- a/gm/beziereffects.cpp
+++ b/gm/beziereffects.cpp
@@ -50,7 +50,7 @@
     }
 
     virtual SkISize onISize() SK_OVERRIDE {
-        return make_isize(800, 800);
+        return SkISize::Make(800, 800);
     }
 
     virtual uint32_t onGetFlags() const SK_OVERRIDE {
@@ -208,7 +208,7 @@
     }
 
     virtual SkISize onISize() SK_OVERRIDE {
-        return make_isize(800, 800);
+        return SkISize::Make(800, 800);
     }
 
     virtual uint32_t onGetFlags() const SK_OVERRIDE {
@@ -399,7 +399,7 @@
     }
 
     virtual SkISize onISize() SK_OVERRIDE {
-        return make_isize(800, 800);
+        return SkISize::Make(800, 800);
     }
 
     virtual uint32_t onGetFlags() const SK_OVERRIDE {