Remove `fs::read_to_string` reimplementations

After two previous PRs already removed some instances of
reimplementations of the `fs::read_to_string` functionality, this
removes the last remaining occurence and with it all instances of
`File::open`. So this should remove them all for good.

alacritty_terminal/src/term/mod.rs

@@ -2663,8 +2663,7 @@ mod benches {
     extern crate serde_json as json;
     extern crate test;
 
-    use std::fs::File;
-    use std::io::Read;
+    use std::fs;
     use std::mem;
     use std::path::Path;
 
@@ -2681,16 +2680,6 @@ mod benches {
         fn send_event(&self, _event: Event) {}
     }
 
-    fn read_string<P>(path: P) -> String
-    where
-        P: AsRef<Path>,
-    {
-        let mut res = String::new();
-        File::open(path.as_ref()).unwrap().read_to_string(&mut res).unwrap();
-
-        res
-    }
-
     /// Benchmark for the renderable cells iterator
     ///
     /// The renderable cells iterator yields cells that require work to be
@@ -2703,14 +2692,16 @@ mod benches {
     #[bench]
     fn render_iter(b: &mut test::Bencher) {
         // Need some realistic grid state; using one of the ref files.
-        let serialized_grid = read_string(concat!(
+        let serialized_grid = fs::read_to_string(concat!(
             env!("CARGO_MANIFEST_DIR"),
             "/tests/ref/vim_large_window_scroll/grid.json"
-        ));
-        let serialized_size = read_string(concat!(
+        ))
+        .unwrap();
+        let serialized_size = fs::read_to_string(concat!(
             env!("CARGO_MANIFEST_DIR"),
             "/tests/ref/vim_large_window_scroll/size.json"
-        ));
+        ))
+        .unwrap();
 
         let mut grid: Grid<Cell> = json::from_str(&serialized_grid).unwrap();
         let size: SizeInfo = json::from_str(&serialized_size).unwrap();

alacritty_terminal/tests/ref.rs

@@ -1,7 +1,7 @@
 use serde::Deserialize;
 use serde_json as json;
 
-use std::fs::{read_to_string, File};
+use std::fs::{self, File};
 use std::io::{self, Read};
 use std::path::Path;
 
@@ -87,9 +87,9 @@ impl EventListener for Mock {
 
 fn ref_test(dir: &Path) {
     let recording = read_u8(dir.join("alacritty.recording"));
-    let serialized_size = read_to_string(dir.join("size.json")).unwrap();
-    let serialized_grid = read_to_string(dir.join("grid.json")).unwrap();
-    let serialized_cfg = read_to_string(dir.join("config.json")).unwrap();
+    let serialized_size = fs::read_to_string(dir.join("size.json")).unwrap();
+    let serialized_grid = fs::read_to_string(dir.join("grid.json")).unwrap();
+    let serialized_cfg = fs::read_to_string(dir.join("config.json")).unwrap();
 
     let size: SizeInfo = json::from_str(&serialized_size).unwrap();
     let grid: Grid<Cell> = json::from_str(&serialized_grid).unwrap();