Shift away from using std::str::from_utf8.

(It's probably being removed, see rust-lang/rust#10701.)

Author: chris-morgan

src/examples/client/main.rs

@@ -47,5 +47,6 @@ fn make_and_print_request(url: ~str) {
         println!(" - {}: {}", header.header_name(), header.header_value());
     }
     println("Body:");
-    println(str::from_utf8(response.read_to_end()));
+    let body = response.read_to_end();
+    println(str::from_utf8_slice(body));
 }

src/http/headers/test_utils.rs

@@ -14,7 +14,7 @@ pub fn from_stream_with_str<T: HeaderConvertible>(s: &str) -> Option<T> {
 pub fn to_stream_into_str<T: HeaderConvertible>(v: &T) -> ~str {
     let mut writer = MemWriter::new();
     v.to_stream(&mut writer);
-    str::from_utf8(writer.inner_ref().as_slice())
+    str::from_utf8_owned(writer.inner_ref().to_owned())
 }
 
 // Verify that a value cannot be successfully interpreted as a header value of the specified type.