allow canvas to force conservative clips (for speed)

tests/AAClipTest.cpp

Index: tests/AAClipTest.cpp
diff --git a/tests/AAClipTest.cpp b/tests/AAClipTest.cpp
index 776cd5267ab6a4a31022394072f78fe4cd462b2d..64e378455a751fb687757b2d75060940c59a2a08 100644
--- a/tests/AAClipTest.cpp
+++ b/tests/AAClipTest.cpp
@@ -371,6 +371,7 @@ static bool operator==(const SkRasterClip& a, const SkRasterClip& b) {
 
 static void did_dx_affect(skiatest::Reporter* reporter, const SkScalar dx[],
                           size_t count, bool changed) {
+    const SkISize baseSize = SkISize::Make(10, 10);
     SkIRect ir = { 0, 0, 10, 10 };
 
     for (size_t i = 0; i < count; ++i) {
@@ -381,11 +382,11 @@ static void did_dx_affect(skiatest::Reporter* reporter, const SkScalar dx[],
         SkRasterClip rc1(ir);
         SkRasterClip rc2(ir);
 
-        rc0.op(r, SkRegion::kIntersect_Op, false);
+        rc0.op(r, baseSize, SkRegion::kIntersect_Op, false);
         r.offset(dx[i], 0);
-        rc1.op(r, SkRegion::kIntersect_Op, true);
+        rc1.op(r, baseSize, SkRegion::kIntersect_Op, true);
         r.offset(-2*dx[i], 0);
-        rc2.op(r, SkRegion::kIntersect_Op, true);
+        rc2.op(r, baseSize, SkRegion::kIntersect_Op, true);
 
         REPORTER_ASSERT(reporter, changed != (rc0 == rc1));
         REPORTER_ASSERT(reporter, changed != (rc0 == rc2));