From e840c7aaa09627979c2cec69277a04f884489e6b Mon Sep 17 00:00:00 2001
From: Patrick Walton <pcwalton@mimiga.net>
Date: Fri, 15 Apr 2016 17:25:24 -0700
Subject: [PATCH] layout: Make absolutely-positioned blocks not generate {ib}
 splits.

Improves YouTube.

Closes #10642.
---
 components/layout/construct.rs                | 27 ++++++++++---------
 tests/wpt/mozilla/meta/MANIFEST.json          | 24 +++++++++++++++++
 .../tests/css/absolute_ib_split_a.html        |  5 ++++
 .../tests/css/absolute_ib_split_ref.html      |  4 +++
 4 files changed, 47 insertions(+), 13 deletions(-)
 create mode 100644 tests/wpt/mozilla/tests/css/absolute_ib_split_a.html
 create mode 100644 tests/wpt/mozilla/tests/css/absolute_ib_split_ref.html

diff --git a/components/layout/construct.rs b/components/layout/construct.rs
index 8ba85710ae3..4099e1f9af5 100644
--- a/components/layout/construct.rs
+++ b/components/layout/construct.rs
@@ -512,19 +512,20 @@ impl<'a, ConcreteThreadSafeLayoutNode: ThreadSafeLayoutNode>
                 } else if flow.need_anonymous_flow(&*kid_flow) {
                     consecutive_siblings.push(kid_flow)
                 } else {
-                    // Flush any inline fragments that we were gathering up. This allows us to
-                    // handle {ib} splits.
-                    debug!("flushing {} inline box(es) to flow A",
-                           inline_fragment_accumulator.fragments.fragments.len());
-                    let old_inline_fragment_accumulator =
-                        mem::replace(inline_fragment_accumulator,
-                                     InlineFragmentsAccumulator::new());
-                    self.flush_inline_fragments_to_flow_or_list(
-                        old_inline_fragment_accumulator,
-                        flow,
-                        consecutive_siblings,
-                        abs_descendants,
-                        node);
+                    if !flow::base(&*kid_flow).flags.contains(IS_ABSOLUTELY_POSITIONED) {
+                        // Flush any inline fragments that we were gathering up. This allows us to
+                        // handle {ib} splits.
+                        let old_inline_fragment_accumulator =
+                            mem::replace(inline_fragment_accumulator,
+                                         InlineFragmentsAccumulator::new());
+                        self.flush_inline_fragments_to_flow_or_list(
+                            old_inline_fragment_accumulator,
+                            flow,
+                            consecutive_siblings,
+                            abs_descendants,
+                            node);
+                    }
+
                     if !consecutive_siblings.is_empty() {
                         let consecutive_siblings = mem::replace(consecutive_siblings, vec!());
                         self.generate_anonymous_missing_child(consecutive_siblings, flow, node);
diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index 121842c43ff..010e2d1e8b3 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -94,6 +94,18 @@
             "url": "/_mozilla/css/absolute_hypothetical_with_intervening_inline_block_a.html"
           }
         ],
+        "css/absolute_ib_split_a.html": [
+          {
+            "path": "css/absolute_ib_split_a.html",
+            "references": [
+              [
+                "/_mozilla/css/absolute_ib_split_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/absolute_ib_split_a.html"
+          }
+        ],
         "css/absolute_inline_containing_block_a.html": [
           {
             "path": "css/absolute_inline_containing_block_a.html",
@@ -6720,6 +6732,18 @@
           "url": "/_mozilla/css/absolute_hypothetical_with_intervening_inline_block_a.html"
         }
       ],
+      "css/absolute_ib_split_a.html": [
+        {
+          "path": "css/absolute_ib_split_a.html",
+          "references": [
+            [
+              "/_mozilla/css/absolute_ib_split_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/absolute_ib_split_a.html"
+        }
+      ],
       "css/absolute_inline_containing_block_a.html": [
         {
           "path": "css/absolute_inline_containing_block_a.html",
diff --git a/tests/wpt/mozilla/tests/css/absolute_ib_split_a.html b/tests/wpt/mozilla/tests/css/absolute_ib_split_a.html
new file mode 100644
index 00000000000..43b8fb09e9e
--- /dev/null
+++ b/tests/wpt/mozilla/tests/css/absolute_ib_split_a.html
@@ -0,0 +1,5 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<link rel="match" href="absolute_ib_split_ref.html">
+Ser<div style="position: absolute"></div>vo
+
diff --git a/tests/wpt/mozilla/tests/css/absolute_ib_split_ref.html b/tests/wpt/mozilla/tests/css/absolute_ib_split_ref.html
new file mode 100644
index 00000000000..6acc697b869
--- /dev/null
+++ b/tests/wpt/mozilla/tests/css/absolute_ib_split_ref.html
@@ -0,0 +1,4 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+Servo
+