Update rustdoc tests

Author: GuillaumeGomez

Diff for: tests/rustdoc/playground-arg.rs

@@ -10,4 +10,4 @@
 pub fn dummy() {}
 
 // ensure that `extern crate foo;` was inserted into code snips automatically:
-//@ matches foo/index.html '//a[@class="test-arrow"][@href="https://example.com/?code=%23!%5Ballow(unused)%5D%0A%23%5Ballow(unused_extern_crates)%5D%0Aextern+crate+r%23foo;%0Afn+main()+%7B%0A++++use+foo::dummy;%0A++++dummy();%0A%7D&edition=2015"]' "Run"
+//@ matches foo/index.html '//a[@class="test-arrow"][@href="https://example.com/?code=%23!%5Ballow(unused)%5D%0A%23%5Ballow(unused_extern_crates)%5D%0Aextern+crate+r%23foo;%0Afn+main()+%7B%0A++++use+foo::dummy;%0A++++dummy();%0A%7D&edition=2015"]' ""

Diff for: tests/rustdoc/playground-syntax-error.rs

@@ -17,5 +17,5 @@
 pub fn bar() {}
 
 //@ has foo/fn.bar.html
-//@ has - '//a[@class="test-arrow"]' "Run"
+//@ has - '//a[@class="test-arrow"]' ""
 //@ has - '//*[@class="docblock"]' 'foo_recursive'

Diff for: tests/rustdoc/playground.rs

@@ -22,6 +22,6 @@
 //! }
 //! ```
 
-//@ matches foo/index.html '//a[@class="test-arrow"][@href="https://www.example.com/?code=%23!%5Ballow(unused)%5D%0Afn+main()+%7B%0A++++println!(%22Hello,+world!%22);%0A%7D&edition=2015"]' "Run"
-//@ matches foo/index.html '//a[@class="test-arrow"][@href="https://www.example.com/?code=%23!%5Ballow(unused)%5D%0Afn+main()+%7B%0A++++println!(%22Hello,+world!%22);%0A%7D&edition=2015"]' "Run"
-//@ matches foo/index.html '//a[@class="test-arrow"][@href="https://www.example.com/?code=%23!%5Ballow(unused)%5D%0A%23!%5Bfeature(something)%5D%0A%0Afn+main()+%7B%0A++++println!(%22Hello,+world!%22);%0A%7D&version=nightly&edition=2015"]' "Run"
+//@ matches foo/index.html '//a[@class="test-arrow"][@href="https://www.example.com/?code=%23!%5Ballow(unused)%5D%0Afn+main()+%7B%0A++++println!(%22Hello,+world!%22);%0A%7D&edition=2015"]' ""
+//@ matches foo/index.html '//a[@class="test-arrow"][@href="https://www.example.com/?code=%23!%5Ballow(unused)%5D%0Afn+main()+%7B%0A++++println!(%22Hello,+world!%22);%0A%7D&edition=2015"]' ""
+//@ matches foo/index.html '//a[@class="test-arrow"][@href="https://www.example.com/?code=%23!%5Ballow(unused)%5D%0A%23!%5Bfeature(something)%5D%0A%0Afn+main()+%7B%0A++++println!(%22Hello,+world!%22);%0A%7D&version=nightly&edition=2015"]' ""