std: Remove String::from_owned_str as it's redundant

[breaking-change]

src/libgetopts/lib.rs

@@ -671,7 +671,7 @@ pub fn usage(brief: &str, opts: &[OptGroup]) -> String {
                      hasarg: hasarg,
                      ..} = (*optref).clone();
 
-        let mut row = String::from_owned_str(" ".repeat(4));
+        let mut row = " ".repeat(4);
 
         // short option
         match short_name.len() {

src/libstd/str.rs

@@ -910,10 +910,9 @@ impl OwnedStr for String {
     }
 
     #[inline]
-    fn append(self, rhs: &str) -> String {
-        let mut new_str = String::from_owned_str(self);
-        new_str.push_str(rhs);
-        new_str
+    fn append(mut self, rhs: &str) -> String {
+        self.push_str(rhs);
+        self
     }
 }
 

src/libstd/string.rs

@@ -68,7 +68,8 @@ impl String {
         }
     }
 
-    /// Creates a new string buffer from the given owned string, taking care not to copy it.
+    #[allow(missing_doc)]
+    #[deprecated = "obsoleted by the removal of ~str"]
     #[inline]
     pub fn from_owned_str(string: String) -> String {
         string

src/libtest/lib.rs

@@ -110,7 +110,7 @@ impl TestDesc {
         use std::num::Saturating;
         let mut name = String::from_str(self.name.as_slice());
         let fill = column_count.saturating_sub(name.len());
-        let mut pad = String::from_owned_str(" ".repeat(fill));
+        let mut pad = " ".repeat(fill);
         match align {
             PadNone => name,
             PadOnLeft => {