go/ast: fix comments misinterpreted as documentation

The comments describing blocks of Pos/End implementations for various
nodes types are being misinterpreted as documentation for BadDecl,
BadExpr, BadStmt, and ImportSpec's Pos methods.

Change-Id: I935b0bc38dbc13e9305f3efeb437dd3a6575d9a1
Reviewed-on: https://go-review.googlesource.com/24152Reviewed-by: Robert Griesemer <gri@golang.org>

src/go/ast/ast.go

@@ -418,7 +418,7 @@ type (
 )
 
 // Pos and End implementations for expression/type nodes.
-//
+
 func (x *BadExpr) Pos() token.Pos  { return x.From }
 func (x *Ident) Pos() token.Pos    { return x.NamePos }
 func (x *Ellipsis) Pos() token.Pos { return x.Ellipsis }
@@ -709,7 +709,7 @@ type (
 )
 
 // Pos and End implementations for statement nodes.
-//
+
 func (s *BadStmt) Pos() token.Pos        { return s.From }
 func (s *DeclStmt) Pos() token.Pos       { return s.Decl.Pos() }
 func (s *EmptyStmt) Pos() token.Pos      { return s.Semicolon }
@@ -854,7 +854,7 @@ type (
 )
 
 // Pos and End implementations for spec nodes.
-//
+
 func (s *ImportSpec) Pos() token.Pos {
 	if s.Name != nil {
 		return s.Name.Pos()
@@ -931,7 +931,7 @@ type (
 )
 
 // Pos and End implementations for declaration nodes.
-//
+
 func (d *BadDecl) Pos() token.Pos  { return d.From }
 func (d *GenDecl) Pos() token.Pos  { return d.TokPos }
 func (d *FuncDecl) Pos() token.Pos { return d.Type.Pos() }