Format visibility of associated consts (#953)

Fixes #951.

src/visitor.rs

@@ -362,7 +362,7 @@ impl<'a> FmtVisitor<'a> {
             }
             ast::ImplItemKind::Const(ref ty, ref expr) => {
                 let rewrite = rewrite_static("const",
-                                             ast::Visibility::Inherited,
+                                             ii.vis,
                                              ii.ident,
                                              ty,
                                              ast::Mutability::Immutable,

tests/source/static.rs

@@ -12,3 +12,7 @@ static mut name: SomeType = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
  pub   static   count  :  u8  = 10 ;
 
 pub const test: &Type = &val;
+
+impl Color {
+    pub const WHITE: u32 = 10;
+}

tests/target/static.rs

@@ -15,3 +15,7 @@ static mut name: SomeType =
 pub static count: u8 = 10;
 
 pub const test: &Type = &val;
+
+impl Color {
+    pub const WHITE: u32 = 10;
+}