Update tests/rustdoc to new test syntax

Author: GuillaumeGomez

tests/rustdoc/asref-for-and-of-local-82465.rs

@@ -4,14 +4,14 @@
 use std::convert::AsRef;
 pub struct Local;
 
-// @has foo/struct.Local.html '//h3[@class="code-header"]' 'impl AsRef<str> for Local'
+//@ has foo/struct.Local.html '//h3[@class="code-header"]' 'impl AsRef<str> for Local'
 impl AsRef<str> for Local {
     fn as_ref(&self) -> &str {
         todo!()
     }
 }
 
-// @has - '//h3[@class="code-header"]' 'impl AsRef<Local> for str'
+//@ has - '//h3[@class="code-header"]' 'impl AsRef<Local> for str'
 impl AsRef<Local> for str {
     fn as_ref(&self) -> &Local {
         todo!()

tests/rustdoc/assoc-consts-version.rs

@@ -8,7 +8,7 @@
 pub struct SomeStruct;
 
 impl SomeStruct {
-    // @has 'foo/struct.SomeStruct.html' \
+    //@ has 'foo/struct.SomeStruct.html' \
     //   '//*[@id="associatedconstant.SOME_CONST"]//span[@class="since"]' '1.1.2'
     #[stable(since="1.1.2", feature="rust2")]
     pub const SOME_CONST: usize = 0;