Rollup merge of #34965 - jonathandturner:multispan_cleanup, r=sanxiyn

Remove unused methods from MultiSpan

Removed a couple of unused methods from MultiSpan.  I thought about batching this with some other changes but wasn't sure when I'd get around to them, so PR for a tiny fix instead.

This can be rollup'd.

src/libsyntax_pos/lib.rs

@@ -193,20 +193,6 @@ pub fn new() -> MultiSpan {
         }
     }
 
-    pub fn from_span(primary_span: Span) -> MultiSpan {
-        MultiSpan {
-            primary_spans: vec![primary_span],
-            span_labels: vec![]
-        }
-    }
-
-    pub fn from_spans(vec: Vec<Span>) -> MultiSpan {
-        MultiSpan {
-            primary_spans: vec,
-            span_labels: vec![]
-        }
-    }
-
     pub fn push_span_label(&mut self, span: Span, label: String) {
         self.span_labels.push((span, label));
     }
@@ -254,7 +240,10 @@ pub fn span_labels(&self) -> Vec<SpanLabel> {
 
 impl From<Span> for MultiSpan {
     fn from(span: Span) -> MultiSpan {
-        MultiSpan::from_span(span)
+        MultiSpan {
+            primary_spans: vec![span],
+            span_labels: vec![]
+        }
     }
 }