[LayoutNG] getComputedStyle("top") percentage on abspos inside inline.

We incorrectly thought that we had no lines, because we looked for
legacy line boxes.

Changed the test to a testharness test, because the text dump has some
space differences between NG and legacy.

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng
Change-Id: Ic2ff3b44e222475fcb07700e99f2f0a965fb72ad
Reviewed-on: https://chromium-review.googlesource.com/c/1280546Reviewed-by: Aleks Totic <atotic@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599692}

third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-features=LayoutNG

@@ -277,7 +277,6 @@ crbug.com/807708 fast/css-intrinsic-dimensions/width-avoid-floats.html [ Failure
 crbug.com/591099 fast/css/absolute-inline-alignment-2.html [ Pass ]
 crbug.com/591099 fast/css/case-transform.html [ Failure ]
 crbug.com/835484 fast/css/focus-ring-recursive-continuations.html [ Failure ]
-crbug.com/591099 fast/css/getComputedStyle/computed-style-percentage-top-with-position-inline.html [ Failure ]
 crbug.com/835484 fast/css/outline-narrowLine.html [ Failure ]
 crbug.com/591099 fast/css3-text/css3-text-decoration/text-underline-position/text-underline-position-under.html [ Failure ]
 crbug.com/591099 fast/events/touch/compositor-touch-hit-rects.html [ Failure ]

third_party/WebKit/LayoutTests/fast/css/getComputedStyle/computed-style-percentage-top-with-position-inline-expected.txt

-PASS computedStyle.getPropertyValue('top') is "40px"
-PASS successfullyParsed is true
-
-TEST COMPLETE
-outer inner

third_party/WebKit/LayoutTests/fast/css/getComputedStyle/computed-style-percentage-top-with-position-inline.html

@@ -3,9 +3,12 @@
     outer
     <div id='inner' style="position:absolute; top:50%; background:blue">inner</div>
 </span>
-<script src="../../../resources/js-test.js"></script>
+<script src="../../../resources/testharness.js"></script>
+<script src="../../../resources/testharnessreport.js"></script>
 <script>
+  test(()=> {
     var inner = document.querySelector("#inner");
     var computedStyle = window.getComputedStyle(inner, null);
-    shouldBeEqualToString("computedStyle.getPropertyValue('top')", "40px");
+    assert_equals(computedStyle.getPropertyValue('top'), "40px");
+  }, "Percentages should be resolved");
 </script>

third_party/blink/renderer/core/layout/layout_box.cc

@@ -4031,11 +4031,8 @@ LayoutUnit LayoutBox::ContainingBlockLogicalHeightForPositioned(
       StyleRef().GetPosition()));
 
   const LayoutInline* flow = ToLayoutInline(containing_block);
-  InlineFlowBox* first = flow->FirstLineBox();
-  InlineFlowBox* last = flow->LastLineBox();
-
   // If the containing block is empty, return a height of 0.
-  if (!first || !last)
+  if (flow->IsEmpty())
     return LayoutUnit();
 
   LayoutUnit height_result;

third_party/blink/renderer/core/layout/layout_inline.h

@@ -185,6 +185,10 @@ class CORE_EXPORT LayoutInline : public LayoutBoxModelObject {
   NGPaintFragment* FirstInlineFragment() const final;
   void SetFirstInlineFragment(NGPaintFragment*) final;
 
+  // Return true if this inline doesn't occur on any lines, i.e. when it creates
+  // no fragments.
+  bool IsEmpty() const { return !FirstLineBox() && !FirstInlineFragment(); }
+
   LayoutBoxModelObject* VirtualContinuation() const final {
     return Continuation();
   }