servo: Merge #4783 - Fix 'inline-block' sizing issues (from mttr:inline_block_percentage); r=mbrubeck

The first commit fixes #3624, and the second commit fixes a bug uncovered by the first fix and caught by a reftest (according to CSS 2.1, inline-blocks should have the shrink-to-fit algorithm run on them when size is set to 'auto'). The two new reftests included here fail before the fix and pass afterwards.

Source-Repo: https://github.com/servo/servo
Source-Revision: 986f9cb5432dc51e37e0c47a4f430c0353c6dc75

servo/components/layout/block.rs

@@ -2153,7 +2153,7 @@ pub trait ISizeAndMarginsComputer {
     /// available_inline-size
     /// where available_inline-size = CB inline-size - (horizontal border + padding)
     fn solve_block_inline_size_constraints(&self,
-                                           _: &mut BlockFlow,
+                                           block: &mut BlockFlow,
                                            input: &ISizeConstraintInput)
                                            -> ISizeConstraintSolution {
         let (computed_inline_size, inline_start_margin, inline_end_margin, available_inline_size) =
@@ -2180,7 +2180,7 @@ pub trait ISizeAndMarginsComputer {
 
         // Invariant: inline-start_margin + inline-size + inline-end_margin ==
         // available_inline-size
-        let (inline_start_margin, inline_size, inline_end_margin) =
+        let (inline_start_margin, mut inline_size, inline_end_margin) =
             match (inline_start_margin, computed_inline_size, inline_end_margin) {
                 // If all have a computed value other than 'auto', the system is
                 // over-constrained so we discard the end margin.
@@ -2213,6 +2213,13 @@ pub trait ISizeAndMarginsComputer {
                     (margin, inline_size, margin)
                 }
             };
+
+        // If inline-size is set to 'auto', and this is an inline block, use the
+        // shrink to fit algorithm (see CSS 2.1 § 10.3.9)
+        if computed_inline_size == MaybeAuto::Auto && block.is_inline_block() {
+            inline_size = block.get_shrink_to_fit_inline_size(inline_size);
+        }
+
         ISizeConstraintSolution::new(inline_size, inline_start_margin, inline_end_margin)
     }
 }

servo/components/layout/inline.rs

@@ -1117,10 +1117,10 @@ impl Flow for InlineFlow {
 
         debug!("InlineFlow::assign_inline_sizes: floats in: {:?}", self.base.floats);
 
-        self.base.position.size.inline = self.base.block_container_inline_size;
+        let inline_size = self.base.block_container_inline_size;
+        self.base.position.size.inline = inline_size;
 
         {
-            let inline_size = self.base.position.size.inline;
             let this = &mut *self;
             for fragment in this.fragments.fragments.iter_mut() {
                 fragment.compute_border_and_padding(inline_size);
@@ -1130,11 +1130,14 @@ impl Flow for InlineFlow {
             }
         }
 
-        // If there are any inline-block kids, propagate explicit block sizes down to them.
+        // If there are any inline-block kids, propagate explicit block and inline
+        // sizes down to them.
         let block_container_explicit_block_size = self.base.block_container_explicit_block_size;
         for kid in self.base.child_iter() {
-            flow::mut_base(kid).block_container_explicit_block_size =
-                block_container_explicit_block_size;
+            let kid_base = flow::mut_base(kid);
+
+            kid_base.block_container_inline_size = inline_size;
+            kid_base.block_container_explicit_block_size = block_container_explicit_block_size;
         }
     }