Clear `self.pending_whitespace.max_content` in `forced_line_break()` (#33469)

If we encountered a preserved line break after some whitespace, we were
including the space in the max-content size of the following line.

So just like `line_break_opportunity()` was already clearing
`self.pending_whitespace.min_content`, `forced_line_break()` needs to
clear `self.pending_whitespace.max_content` too.

Also some cosmetic refactoring.

Signed-off-by: Oriol Brufau <obrufau@igalia.com>

3 files changed, 33 insertions, 9 deletions

diff --git a/components/layout_2020/flow/inline/mod.rs b/components/layout_2020/flow/inline/mod.rs
index f03fc94d407..8a0b86c1c7d 100644
--- a/components/layout_2020/flow/inline/mod.rs
+++ b/components/layout_2020/flow/inline/mod.rs
@@ -2354,7 +2354,6 @@ impl<'layout_data> ContentSizesComputation<'layout_data> {
                             // and start measuring from the inline origin once more.
                             if run.is_single_preserved_newline() {
                                 self.forced_line_break();
-                                self.current_line = ContentSizes::zero();
                                 continue;
                             }
                             if !matches!(
@@ -2430,18 +2429,19 @@ impl<'layout_data> ContentSizesComputation<'layout_data> {
         // it needs to either hang or be removed. If that isn't the case,
         // `commit_pending_whitespace()` should be called first.
         self.pending_whitespace.min_content = Au::zero();
-        self.paragraph.min_content =
-            std::cmp::max(self.paragraph.min_content, self.current_line.min_content);
-        self.current_line.min_content = Au::zero();
+        let current_min_content = mem::take(&mut self.current_line.min_content);
+        self.paragraph.min_content.max_assign(current_min_content);
         self.had_content_yet_for_min_content = false;
     }
 
     fn forced_line_break(&mut self) {
+        // Handle the line break for min-content sizes.
         self.line_break_opportunity();
-        self.paragraph.max_content =
-            std::cmp::max(self.paragraph.max_content, self.current_line.max_content);
-        self.current_line.max_content = Au::zero();
-        self.had_content_yet_for_min_content = false;
+
+        // Repeat the same logic, but now for max-content sizes.
+        self.pending_whitespace.max_content = Au::zero();
+        let current_max_content = mem::take(&mut self.current_line.max_content);
+        self.paragraph.max_content.max_assign(current_max_content);
         self.had_content_yet_for_max_content = false;
     }
 
diff --git a/tests/wpt/meta/MANIFEST.json b/tests/wpt/meta/MANIFEST.json
index 66db19e3b25..e35446a99bd 100644
--- a/tests/wpt/meta/MANIFEST.json
+++ b/tests/wpt/meta/MANIFEST.json
@@ -567209,7 +567209,7 @@
        ]
       ],
       "white-space-intrinsic-size-021.html": [
-       "a209f72c30a5a48ed4c185f9d3962abeb68399fb",
+       "f9c246d4899b58dbcf2dc08655c8bc1f39995e5a",
        [
         null,
         {}
diff --git a/tests/wpt/tests/css/css-text/white-space/white-space-intrinsic-size-021.html b/tests/wpt/tests/css/css-text/white-space/white-space-intrinsic-size-021.html
index a209f72c30a..f9c246d4899 100644
--- a/tests/wpt/tests/css/css-text/white-space/white-space-intrinsic-size-021.html
+++ b/tests/wpt/tests/css/css-text/white-space/white-space-intrinsic-size-021.html
@@ -26,6 +26,10 @@
 hr {
   clear: both;
 }
+x-br::before {
+  content: "\a";
+  white-space: preserve-breaks;
+}
 .collapse.wrap {
   white-space: normal;
 }
@@ -152,6 +156,16 @@ hr {
   <div class="break-spaces wrap"      data-expected-client-width="20" data-expected-client-height="20">X  É</div>
   <div class="break-spaces nowrap"    data-expected-client-width="40" data-expected-client-height="10">X  É</div>
 </div>
+<div class="container narrow">
+  <div class="collapse wrap"          data-expected-client-width="10" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="collapse nowrap"        data-expected-client-width="10" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="preserve wrap"          data-expected-client-width="10" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="preserve nowrap"        data-expected-client-width="20" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="preserve-breaks wrap"   data-expected-client-width="10" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="preserve-breaks nowrap" data-expected-client-width="10" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="break-spaces wrap"      data-expected-client-width="20" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="break-spaces nowrap"    data-expected-client-width="20" data-expected-client-height="20">X <x-br></x-br>É</div>
+</div>
 
 <hr>
 
@@ -255,6 +269,16 @@ hr {
   <div class="break-spaces wrap"      data-expected-client-width="40" data-expected-client-height="10">X  É</div>
   <div class="break-spaces nowrap"    data-expected-client-width="40" data-expected-client-height="10">X  É</div>
 </div>
+<div class="container wide">
+  <div class="collapse wrap"          data-expected-client-width="10" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="collapse nowrap"        data-expected-client-width="10" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="preserve wrap"          data-expected-client-width="20" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="preserve nowrap"        data-expected-client-width="20" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="preserve-breaks wrap"   data-expected-client-width="10" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="preserve-breaks nowrap" data-expected-client-width="10" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="break-spaces wrap"      data-expected-client-width="20" data-expected-client-height="20">X <x-br></x-br>É</div>
+  <div class="break-spaces nowrap"    data-expected-client-width="20" data-expected-client-height="20">X <x-br></x-br>É</div>
+</div>
 
 <hr>