Use injection syntax trees for bracket matching

Previously we used the root syntax tree for bracket matching. We can use
the new functionality in `Syntax` for finding the correct syntax tree
for a given byte range though so we use the correct syntax tree within
injections. This improves bracket matching behavior within HTML
injections like script or style tags for example.

helix-core/src/match_brackets.rs

@@ -57,10 +57,10 @@ fn find_pair(
     pos_: usize,
     traverse_parents: bool,
 ) -> Option<usize> {
-    let tree = syntax.tree();
     let pos = doc.char_to_byte(pos_);
 
-    let mut node = tree.root_node().descendant_for_byte_range(pos, pos + 1)?;
+    let root = syntax.tree_for_byte_range(pos, pos + 1).root_node();
+    let mut node = root.descendant_for_byte_range(pos, pos + 1)?;
 
     loop {
         if node.is_named() {
@@ -118,9 +118,7 @@ fn find_pair(
         };
         node = parent;
     }
-    let node = tree
-        .root_node()
-        .named_descendant_for_byte_range(pos, pos + 1)?;
+    let node = root.named_descendant_for_byte_range(pos, pos + 1)?;
     if node.child_count() != 0 {
         return None;
     }

helix-core/src/syntax.rs

@@ -1338,7 +1338,7 @@ impl Syntax {
         result
     }
 
-    pub fn descendant_for_byte_range(&self, start: usize, end: usize) -> Option<Node<'_>> {
+    pub fn tree_for_byte_range(&self, start: usize, end: usize) -> &Tree {
         let mut container_id = self.root;
 
         for (layer_id, layer) in self.layers.iter() {
@@ -1349,8 +1349,11 @@ impl Syntax {
             }
         }
 
-        self.layers[container_id]
-            .tree()
+        self.layers[container_id].tree()
+    }
+
+    pub fn descendant_for_byte_range(&self, start: usize, end: usize) -> Option<Node<'_>> {
+        self.tree_for_byte_range(start, end)
             .root_node()
             .descendant_for_byte_range(start, end)
     }