Cherry pick to M48: give up on quad root if infinite

src/core/SkGeometry.cpp

Index: src/core/SkGeometry.cpp
diff --git a/src/core/SkGeometry.cpp b/src/core/SkGeometry.cpp
index 01b618073ab1741648fc2f0e1fdc5ad9b40b3a43..2e5888dfb52c14d3440b08d6de03fe5f285b8a9f 100644
--- a/src/core/SkGeometry.cpp
+++ b/src/core/SkGeometry.cpp
@@ -90,7 +90,7 @@ int SkFindUnitQuadRoots(SkScalar A, SkScalar B, SkScalar C, SkScalar roots[2]) {
     SkScalar* r = roots;
 
     SkScalar R = B*B - 4*A*C;
-    if (R < 0 || SkScalarIsNaN(R)) {  // complex roots
+    if (R < 0 || !SkScalarIsFinite(R)) {  // complex roots
         return 0;
     }
     R = SkScalarSqrt(R);