harden and speed up path op unit tests

PathOps tests internal routines direcctly. Check to make sure that
test points, lines, quads, curves, triangles, and bounds read from
arrays are valid (i.e., don't contain NaN) before calling the
test function.

Repurpose the test flags.
- make 'v' verbose test region output against path output
- make 'z' single threaded (before it made it multithreaded)

The latter change speeds up tests run by the buildbot by 2x to 3x.

BUG=

Review URL: https://codereview.chromium.org/19374003

git-svn-id: http://skia.googlecode.com/svn/trunk@10107 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/PathOpsDLineTest.cpp b/tests/PathOpsDLineTest.cpp
index c237494..feab21d 100644
--- a/tests/PathOpsDLineTest.cpp
+++ b/tests/PathOpsDLineTest.cpp
@@ -4,6 +4,7 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
+#include "PathOpsTestCommon.h"
 #include "SkPathOpsLine.h"
 #include "Test.h"
 
@@ -30,11 +31,13 @@
 static void PathOpsLineUtilitiesTest(skiatest::Reporter* reporter) {
     for (size_t index = 0; index < tests_count; ++index) {
         const SkDLine& line = tests[index];
+        SkASSERT(ValidLine(line));
         SkDLine line2;
         SkPoint pts[2] = {line[0].asSkPoint(), line[1].asSkPoint()};
         line2.set(pts);
         REPORTER_ASSERT(reporter, line[0] == line2[0] && line[1] == line2[1]);
         const SkDPoint& pt = left[index];
+        SkASSERT(ValidPoint(pt));
         double result = line.isLeft(pt);
         if ((result <= 0 && index >= 1) || (result < 0 && index == 0)) {
             SkDebugf("%s [%d] expected left\n", __FUNCTION__, index);