Fix some formatting.

Author: nnethercote

compiler/rustc_span/src/symbol.rs

@@ -119,8 +119,8 @@ symbols! {
         MacroRules:         "macro_rules",
         Raw:                "raw",
         Reuse:              "reuse",
-        ContractEnsures:  "contract_ensures",
-        ContractRequires: "contract_requires",
+        ContractEnsures:    "contract_ensures",
+        ContractRequires:   "contract_requires",
         Safe:               "safe",
         Union:              "union",
         Yeet:               "yeet",