```flush to zero tiny radii

Bug: 850350
Change-Id: If1f8efdb02782d520195a6b66bd159628c89f811
```
```diff --git a/src/core/SkRRect.cpp b/src/core/SkRRect.cpp
index 01e76d5..6a6b24b 100644
--- a/src/core/SkRRect.cpp
+++ b/src/core/SkRRect.cpp
```
```@@ -173,8 +173,20 @@
return true;
}

+// If we can't distinguish one of the radii relative to the other, force it to zero so it
+// doesn't confuse us later. See crbug.com/850350
+//
+static void flush_to_zero(SkScalar& a, SkScalar& b) {
+    SkASSERT(a >= 0);
+    SkASSERT(b >= 0);
+    if (a + b == a) {
+        b = 0;
+    } else if (a + b == b) {
+        a = 0;
+    }
+}

// Proportionally scale down all radii to fit. Find the minimum ratio
// of a side and the radii on that side (for all four sides) and use
// that to scale down _all_ the radii. This algorithm is from the
@@ -195,6 +207,11 @@

+
if (scale < 1.0) {
```
```diff --git a/tests/RegionTest.cpp b/tests/RegionTest.cpp
index cdfb2b1..0b8872a 100644
--- a/tests/RegionTest.cpp
+++ b/tests/RegionTest.cpp
```
```@@ -444,7 +444,7 @@
rgn.setPath(path, SkRegion(ir));
}

-DEF_TEST(rrect_region, reporter) {
+DEF_TEST(rrect_region_crbug_850350, reporter) {
SkMatrix m;
m.reset();
m[1] = 0.753662348f;
@@ -464,9 +464,6 @@
path.transform(m);

SkRegion rgn;
-    if (false) {
-        // this assserts in the debug build. see crbug.com/850350
-        rgn.setPath(path, SkRegion{SkIRect{0, 0, 24, 24}});
-    }
+    rgn.setPath(path, SkRegion{SkIRect{0, 0, 24, 24}});
}

```