Allow negative error for Sk4f::sqrt() test.

BUG=skia:

Review URL: https://codereview.chromium.org/1028743002
diff --git a/tests/Sk4xTest.cpp b/tests/Sk4xTest.cpp
index cdd7d56..d7a016c 100644
--- a/tests/Sk4xTest.cpp
+++ b/tests/Sk4xTest.cpp
@@ -93,13 +93,13 @@
            roots(2,  4,  5,  11);
     // .sqrt() should be pretty precise.
     Sk4f error = roots.subtract(squares.sqrt());
-    REPORTER_ASSERT(r, error.greaterThanEqual(Sk4f(0.0f)).allTrue());
-    REPORTER_ASSERT(r, error.lessThan(Sk4f(0.000001f)).allTrue());
+    REPORTER_ASSERT(r, (error > Sk4f(-0.000001f)).allTrue());
+    REPORTER_ASSERT(r, (error < Sk4f(+0.000001f)).allTrue());
 
     // .rsqrt() isn't so precise (for SSE), but should be pretty close.
     error = roots.subtract(squares.multiply(squares.rsqrt()));
-    REPORTER_ASSERT(r, error.greaterThanEqual(Sk4f(0.0f)).allTrue());
-    REPORTER_ASSERT(r, error.lessThan(Sk4f(0.01f)).allTrue());
+    REPORTER_ASSERT(r, (error > Sk4f(-0.01f)).allTrue());
+    REPORTER_ASSERT(r, (error < Sk4f(+0.01f)).allTrue());
 }
 
 DEF_TEST(Sk4x_Comparison, r) {