[LayoutNG] Remove shrink-to-fit optimization.

For NG types this isn't needed anymore. The NG types now use:
CalculateSizeBasedLayoutCacheStatusWithGeometry

Which determines the size of a fragment ahead of time, and applies the
same optimization.

The only thing that we now miss, is things which are sized shrink-to-fit
which use legacy layout.

We couldn't apply this optimization to shrink-to-fit tables, as they
may have %-based inline-sized children which affect their (final) inline
size.

Bug: 984642
Change-Id: I0d0b584f31947bb674f4e7e5d88d7af6cf5d9d98
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1662535
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Reviewed-by: Christian Biesinger <cbiesinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#680095}

third_party/blink/renderer/core/layout/ng/ng_layout_utils.cc

@@ -21,60 +21,6 @@ namespace {
 // kMainSize - width / height
 enum class LengthResolveType { kMinSize, kMaxSize, kMainSize };
 
-bool ContentShrinkToFitMayChange(const ComputedStyle& style,
-                                 const NGConstraintSpace& new_space,
-                                 const NGConstraintSpace& old_space,
-                                 const NGLayoutResult& layout_result) {
-  if (old_space.AvailableSize().inline_size ==
-      new_space.AvailableSize().inline_size)
-    return false;
-
-  NGBoxStrut margins = ComputeMarginsForSelf(new_space, style);
-
-#if DCHECK_IS_ON()
-  // The margins must be the same, as this function won't be called if we have
-  // percentage inline margins, and the percentage resolution size changes.
-  NGBoxStrut old_margins = ComputeMarginsForSelf(old_space, style);
-  DCHECK_EQ(margins.inline_start, old_margins.inline_start);
-  DCHECK_EQ(margins.inline_end, old_margins.inline_end);
-#endif
-
-  LayoutUnit old_available_inline_size =
-      std::max(LayoutUnit(),
-               old_space.AvailableSize().inline_size - margins.InlineSum());
-  LayoutUnit new_available_inline_size =
-      std::max(LayoutUnit(),
-               new_space.AvailableSize().inline_size - margins.InlineSum());
-
-  LayoutUnit inline_size =
-      NGFragment(style.GetWritingMode(), layout_result.PhysicalFragment())
-          .InlineSize();
-
-  // If the previous fragment was at its min-content size (indicated by the old
-  // available size being smaller than the fragment), we may be able to skip
-  // layout if the new available size is also smaller.
-  bool unaffected_as_min_content_size =
-      old_available_inline_size < inline_size &&
-      new_available_inline_size <= inline_size;
-
-  // If the previous fragment was at its max-content size (indicated by the old
-  // available size being larger than the fragment), we may be able to skip
-  // layout if the new available size is also larger.
-  bool unaffected_as_max_content_size =
-      old_available_inline_size > inline_size &&
-      new_available_inline_size >= inline_size;
-
-  // TODO(crbug.com/935634): There is an additional optimization where if we
-  // detect (by setting a flag in the layout result) that the
-  // min-content == max-content we can simply just skip layout, as the
-  // available size won't have any effect.
-
-  if (unaffected_as_min_content_size || unaffected_as_max_content_size)
-    return false;
-
-  return true;
-}
-
 inline bool InlineLengthMayChange(const ComputedStyle& style,
                                   const Length& length,
                                   LengthResolveType type,
@@ -100,20 +46,6 @@ inline bool InlineLengthMayChange(const ComputedStyle& style,
        old_space.PercentageResolutionInlineSize()))
     return true;
 
-  // For elements which shrink to fit, we can perform a specific optimization
-  // where we can skip relayout if the element was sized to its min-content or
-  // max-content size.
-  bool is_content_shrink_to_fit =
-      type == LengthResolveType::kMainSize &&
-      (new_space.IsShrinkToFit() || length.IsFitContent());
-
-  // TODO(ikilpatrick): Test if we can remove this optimization now that we
-  // compute the initial size of the fragment.
-  if (is_content_shrink_to_fit) {
-    return ContentShrinkToFitMayChange(style, new_space, old_space,
-                                       layout_result);
-  }
-
   if (is_unspecified) {
     if (new_space.AvailableSize().inline_size !=
         old_space.AvailableSize().inline_size)

third_party/blink/web_tests/external/wpt/css/css-tables/percent-width-cell-dynamic.html

+<!DOCTYPE html>
+<link rel="help" href="https://crbug.com/984642" />
+<link rel="match" href="../reference/ref-filled-green-100px-square-only.html">
+<style>
+html { overflow: hidden; }
+</style>
+<p>Test passes if there is a filled green square.</p>
+<div id="target">
+  <div style="width: 10%;">
+    <div style="display: inline-table;">
+      <div style="display: table-cell; width: 100%;">
+        <span style="display: inline-block; width: 100%; height: 100px; background: green;"></span>
+      </div>
+      <div style="display: table-cell;">
+        <span style="display: inline-block; width: 10px; height: 100px; background: green;"></span>
+      </div>
+     </div>
+  </div>
+</div>
+<script>
+document.body.offsetTop;
+document.getElementById('target').style.width = '1000px';
+</script>