Check if fragment's block size fits into a layout opportunity.

Since we started using LayoutOpportunity iterator for positioning BFC
fragments, we can't longer rely on the assumption that
FindLayoutOpportunityForFragment will be used for floats only.

List of changes:
- Change FindLayoutOpportunityForFragment to check if fragment's block
  size fits into a layout opportunity.
- Change NGInlineLayoutAlgorithm to avoid adding font's descent to
  line_bottom if the text only includes object replacement characters
  I need it to fix floats-wrap-top-below-002l-ref.xht.

BUG=635619

Review-Url: https://codereview.chromium.org/2840883002
Cr-Commit-Position: refs/heads/master@{#467875}

third_party/WebKit/Source/core/layout/ng/inline/ng_inline_layout_algorithm.cc

@@ -49,6 +49,11 @@ NGLogicalOffset GetOriginPointForFloats(const NGConstraintSpace& space,
   origin_point.block_offset += content_size;
   return origin_point;
 }
+
+inline bool IsObjectReplacementCharacter(UChar character) {
+  return character == kObjectReplacementCharacter;
+}
+
 }  // namespace
 
 NGInlineLayoutAlgorithm::NGInlineLayoutAlgorithm(
@@ -474,7 +479,12 @@ bool NGInlineLayoutAlgorithm::PlaceItems(
   baseline = LayoutUnit(baseline.Round());
 
   // Check if the line fits into the constraint space in block direction.
-  LayoutUnit line_bottom = baseline + line_box.Metrics().descent;
+  LayoutUnit line_bottom = baseline;
+
+  // See http://crrev.com/2840883002
+  if (!Node()->Text().IsAllSpecialCharacters<IsObjectReplacementCharacter>())
+    line_bottom += line_box.Metrics().descent;
+
   if (!container_builder_.Children().IsEmpty() &&
       ConstraintSpace().AvailableSize().block_size != NGSizeIndefinite &&
       line_bottom > ConstraintSpace().AvailableSize().block_size) {

third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.cc

@@ -416,10 +416,13 @@ NGLogicalOffset NGBlockLayoutAlgorithm::PositionNewFc(
   PositionFloats(curr_bfc_offset_.block_offset, curr_bfc_offset_.block_offset,
                  container_builder_.UnpositionedFloats(), tmp_space.Get());
 
+  NGLogicalOffset origin_offset = curr_bfc_offset_;
+  origin_offset.inline_offset += border_and_padding_.inline_start;
+
   // 2. Find an estimated layout opportunity for our fragment.
   NGLayoutOpportunity opportunity = FindLayoutOpportunityForFragment(
-      tmp_space->Exclusions().get(), child_space.AvailableSize(),
-      curr_bfc_offset_, curr_child_margins_, fragment);
+      tmp_space->Exclusions().get(), child_space.AvailableSize(), origin_offset,
+      curr_child_margins_, fragment);
 
   // 3. If the found opportunity lies on the same line with our estimated
   //    child's BFC offset then merge fragment's margins with the current
@@ -435,11 +438,14 @@ NGLogicalOffset NGBlockLayoutAlgorithm::PositionNewFc(
   PositionPendingFloats(curr_bfc_offset_.block_offset, &container_builder_,
                         MutableConstraintSpace());
 
+  origin_offset = curr_bfc_offset_;
+  origin_offset.inline_offset += border_and_padding_.inline_start;
+
   // 5. Find the final layout opportunity for the fragment after all pending
   // floats are positioned at the correct BFC block's offset.
   opportunity = FindLayoutOpportunityForFragment(
       MutableConstraintSpace()->Exclusions().get(), child_space.AvailableSize(),
-      curr_bfc_offset_, curr_child_margins_, fragment);
+      origin_offset, curr_child_margins_, fragment);
 
   curr_bfc_offset_ = opportunity.offset;
   return curr_bfc_offset_;

third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_iterator.cc

@@ -271,10 +271,10 @@ NGLayoutOpportunity FindLayoutOpportunityForFragment(
   NGLayoutOpportunity opportunity_candidate = opportunity_iter.Next();
   while (!opportunity_candidate.IsEmpty()) {
     opportunity = opportunity_candidate;
-    // Checking opportunity's block size is not necessary as a float cannot be
-    // positioned on top of another float inside of the same constraint space.
     auto fragment_inline_size = fragment.InlineSize() + margins.InlineSum();
-    if (opportunity.size.inline_size >= fragment_inline_size)
+    auto fragment_block_size = fragment.BlockSize() + margins.BlockSum();
+    if (opportunity.size.inline_size >= fragment_inline_size &&
+        opportunity.size.block_size >= fragment_block_size)
       break;
     opportunity_candidate = opportunity_iter.Next();
   }