change isNestedRect to isNestedFillRect

R=reed@google.com, bsalomon@google.com

Let isNested(Fill)Rect return true if drawn path describes filled
rectangles.

Review URL: https://codereview.chromium.org/1073473002
diff --git a/tests/StrokeTest.cpp b/tests/StrokeTest.cpp
index 80ca317..b8abbd3 100644
--- a/tests/StrokeTest.cpp
+++ b/tests/StrokeTest.cpp
@@ -74,7 +74,7 @@
 
         bool isMiter = SkPaint::kMiter_Join == joins[i];
         SkRect nested[2];
-        REPORTER_ASSERT(reporter, fillPath.isNestedRects(nested) == isMiter);
+        REPORTER_ASSERT(reporter, fillPath.isNestedFillRects(nested) == isMiter);
         if (isMiter) {
             SkRect inner(r);
             inner.inset(width/2, width/2);