testsuite/doc: Check the arguments used to invoke the browser

Previously we apparently weren't doing this as we weren't checking
stdout.

Author: lf-

tests/testsuite/doc.rs

@@ -1184,6 +1184,7 @@ fn doc_workspace_open_different_library_and_package_names() {
         .env("BROWSER", "echo")
         .with_stderr_contains("[..] Documenting foo v0.1.0 ([..])")
         .with_stderr_contains("[..] [CWD]/target/doc/foolib/index.html")
+        .with_stdout_contains("[CWD]/target/doc/foolib/index.html")
         .run();
 
     p.change_file(
@@ -1197,7 +1198,7 @@ fn doc_workspace_open_different_library_and_package_names() {
     // check that the cargo config overrides the browser env var
     p.cargo("doc --open")
         .env("BROWSER", "true")
-        .with_stdout_contains("[..]a [CWD]/target/doc/foolib/index.html")
+        .with_stdout_contains("a [CWD]/target/doc/foolib/index.html")
         .run();
 }