ensure that negative zeros are still ignored when computing isIdentity()

crbug.com/162747



git-svn-id: http://skia.googlecode.com/svn/trunk@8761 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/Matrix44Test.cpp b/tests/Matrix44Test.cpp
index bdeafd4..b2c7071 100644
--- a/tests/Matrix44Test.cpp
+++ b/tests/Matrix44Test.cpp
@@ -231,6 +231,17 @@
 
     matrix.set(3, 2, 1);
     REPORTER_ASSERT(reporter, matrix.getType() & SkMatrix44::kPerspective_Mask);
+
+    // ensure that negative zero is treated as zero
+    SkMScalar dx = 0;
+    SkMScalar dy = 0;
+    SkMScalar dz = 0;
+    matrix.setTranslate(-dx, -dy, -dz);
+    REPORTER_ASSERT(reporter, matrix.isIdentity());
+    matrix.preTranslate(-dx, -dy, -dz);
+    REPORTER_ASSERT(reporter, matrix.isIdentity());
+    matrix.postTranslate(-dx, -dy, -dz);
+    REPORTER_ASSERT(reporter, matrix.isIdentity());
 }
 
 static void test_common_angles(skiatest::Reporter* reporter) {