[librsvg] length: remove recently add FromStr impl

[Paolo Borelli <pborelli src gnome org>]

commit 739850436da2bbaf5971b080795b16b441daef95
Author: Paolo Borelli <pborelli gnome org>
Date:   Wed Mar 28 22:15:41 2018 +0200

    length: remove recently add FromStr impl
    
    It is not needed anymore and it is questionable since it assumes
    that LengthDir is Both

 rsvg_internals/src/length.rs | 9 ---------
 1 file changed, 9 deletions(-)
---
diff --git a/rsvg_internals/src/length.rs b/rsvg_internals/src/length.rs
index 953fc2b0..50a38fa7 100644
--- a/rsvg_internals/src/length.rs
+++ b/rsvg_internals/src/length.rs
@@ -6,7 +6,6 @@ use regex::Regex;
 
 use std::f64::consts::*;
 use std::ptr;
-use std::str::FromStr;
 
 use drawing_ctx;
 use drawing_ctx::RsvgDrawingCtx;
@@ -139,14 +138,6 @@ impl Parse for RsvgLength {
     }
 }
 
-impl FromStr for RsvgLength {
-    type Err = AttributeError;
-
-    fn from_str(s: &str) -> Result<RsvgLength, AttributeError> {
-        RsvgLength::parse(s, LengthDir::Both)
-    }
-}
-
 impl RsvgLength {
     pub fn new(l: f64, unit: LengthUnit, dir: LengthDir) -> RsvgLength {
         RsvgLength {