Remove `whitespace_around_ops` pending re-name and re-design (#249).

lib/src/rules/whitespace_around_ops.dart

-// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-library linter.src.rules.whitespace_around_ops;
-
-import 'package:analyzer/dart/ast/ast.dart';
-import 'package:analyzer/dart/ast/token.dart';
-import 'package:analyzer/dart/ast/visitor.dart';
-import 'package:linter/src/linter.dart';
-
-const desc = r'Use proper whitespace around operators.';
-
-const details = r'''
-**DO** ensure that there are spaces around binary operators and before any
-unary ones.
-
-Improper whitespace can create confusion, especially when applied to operators
-where it's possible to get a binary operator when you mean a unary one.  For
-example, the mistyping of `5 /~ 10` when you mean `5 ~/ 10` is hidden by the
-improper spacing.  (Properly spaced, the mistake is more clear: `5 / ~10`.)
-Whenever possible, use the formatter to cleanup whitespace.  Otherwise, take
-care to ensure that there are spaces around binary operators and before any
-unary ones.
-
-
-**BAD:**
-```
-print(5 /~ 10); //whoops
-```
-
-**GOOD:**
-```
-print(5 / ~10); //aha!
-```
-''';
-
-class Visitor extends SimpleAstVisitor {
-  final LintRule rule;
-  Visitor(this.rule);
-
-  @override
-  visitBinaryExpression(BinaryExpression node) {
-    if (!spaced(node.leftOperand.endToken, node.operator) ||
-        !spaced(node.operator, node.rightOperand.beginToken)) {
-      rule.reportLintForToken(node.operator);
-    }
-  }
-
-  @override
-  visitPrefixExpression(PrefixExpression node) {
-    if (spaced(node.operator, node.operand.beginToken)) {
-      rule.reportLintForToken(node.operator);
-    }
-  }
-
-  static bool spaced(Token first, Token second) =>
-      first != null && second != null && first.end != second.offset;
-}
-
-class WhitespaceAroundOps extends LintRule {
-  WhitespaceAroundOps()
-      : super(
-            name: 'whitespace_around_ops',
-            description: desc,
-            details: details,
-            group: Group.style);
-
-  @override
-  AstVisitor getVisitor() => new Visitor(this);
-}