Auto merge of #14274 - stshine:servo-url-index, r=emilio

Implement range index with the Position enum on ServoUrl

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because refactoring

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r? @emilio

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components/url/lib.rs

@@ -19,9 +19,10 @@ extern crate url;
 
 use std::fmt;
 use std::net::IpAddr;
+use std::ops::{Range, RangeFrom, RangeTo, RangeFull, Index};
 use std::path::Path;
 use std::sync::Arc;
-use url::{Url, Origin};
+use url::{Url, Origin, Position};
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf, Serialize, Deserialize))]
@@ -152,3 +153,31 @@ impl fmt::Display for ServoUrl {
         self.0.fmt(formatter)
     }
 }
+
+impl Index<RangeFull> for ServoUrl {
+    type Output = str;
+    fn index(&self, _: RangeFull) -> &str {
+        &self.0[..]
+    }
+}
+
+impl Index<RangeFrom<Position>> for ServoUrl {
+    type Output = str;
+    fn index(&self, range: RangeFrom<Position>) -> &str {
+        &self.0[range]
+    }
+}
+
+impl Index<RangeTo<Position>> for ServoUrl {
+    type Output = str;
+    fn index(&self, range: RangeTo<Position>) -> &str {
+        &self.0[range]
+    }
+}
+
+impl Index<Range<Position>> for ServoUrl {
+    type Output = str;
+    fn index(&self, range: Range<Position>) -> &str {
+        &self.0[range]
+    }
+}