Add bigtileimagefilter GM & improvements to toString

src/effects/SkTileImageFilter.cpp

Index: src/effects/SkTileImageFilter.cpp
diff --git a/src/effects/SkTileImageFilter.cpp b/src/effects/SkTileImageFilter.cpp
index c5cf51871da4aab697086e21db0611afc3dcae1b..b2244b9629042e121653b3e4e884bf207775bc3b 100644
--- a/src/effects/SkTileImageFilter.cpp
+++ b/src/effects/SkTileImageFilter.cpp
@@ -110,6 +110,15 @@ void SkTileImageFilter::flatten(SkWriteBuffer& buffer) const {
 #ifndef SK_IGNORE_TO_STRING
 void SkTileImageFilter::toString(SkString* str) const {
     str->appendf("SkTileImageFilter: (");
+    str->appendf("src: %.2f %.2f %.2f %.2f",
+                 fSrcRect.fLeft, fSrcRect.fTop, fSrcRect.fRight, fSrcRect.fBottom);
+    str->appendf(" dst: %.2f %.2f %.2f %.2f",
+                 fDstRect.fLeft, fDstRect.fTop, fDstRect.fRight, fDstRect.fBottom);
+    if (this->getInput(0)) {
+        str->appendf("input: (");
+        this->getInput(0)->toString(str);
+        str->appendf(")");
+    }
     str->append(")");
 }
 #endif