CSS Paths: fix horizontal/vertical commands

The coordinates after H and V commands were being calculated
incorrectly during path serialization.

BUG=887871

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ia2f55213c4a4837d82f9783d1ad1af29de9937ae
Reviewed-on: https://chromium-review.googlesource.com/1252229Reviewed-by: Fredrik Söderquist <fs@opera.com>
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595422}

third_party/WebKit/LayoutTests/external/wpt/css/motion/offset-path-serialization.html

@@ -36,6 +36,10 @@ test(function() {
   target.style.offsetPath = '  path(  "m 10 20 a 10 20 30 1 0 40 50 a 110 120 30 1 1 140 50"  )  ';
   assert_equals(target.style.offsetPath, 'path("m 10 20 a 10 20 30 1 0 40 50 a 110 120 30 1 1 140 50")');
   assert_equals(getComputedStyle(target).offsetPath, 'path("M 10 20 A 10 20 30 1 0 50 70 A 110 120 30 1 1 190 120")');
+
+  target.style.offsetPath = 'path("M 1 2 H 3 v 4 h 5 V 6 h 7 v 8")';
+  assert_equals(target.style.offsetPath, 'path("M 1 2 H 3 v 4 h 5 V 6 h 7 v 8")');
+  assert_equals(getComputedStyle(target).offsetPath, 'path("M 1 2 H 3 V 6 H 8 V 6 H 15 V 14")');
 });
 </script>
 </body>

third_party/blink/renderer/core/svg/svg_path_parser.cc

@@ -291,6 +291,10 @@ void SVGPathAbsolutizer::EmitSegment(const PathSegmentData& segment) {
 
   if (absolute_segment.command == kPathSegClosePath) {
     current_point_ = sub_path_point_;
+  } else if (absolute_segment.command == kPathSegLineToHorizontalAbs) {
+    current_point_.SetX(absolute_segment.target_point.X());
+  } else if (absolute_segment.command == kPathSegLineToVerticalAbs) {
+    current_point_.SetY(absolute_segment.target_point.Y());
   } else {
     current_point_ = absolute_segment.target_point;
     if (absolute_segment.command == kPathSegMoveToAbs) {