more housecleaning: helpers on rules

lib/src/checker/rules.dart

Index: lib/src/checker/rules.dart
diff --git a/lib/src/checker/rules.dart b/lib/src/checker/rules.dart
index c300cea4ab1554ddb3245e6547e4f533dd343b41..ef04cf18bd253efe28a10a474e6aa2bca8a96921 100644
--- a/lib/src/checker/rules.dart
+++ b/lib/src/checker/rules.dart
@@ -32,20 +32,6 @@ abstract class TypeRules {
           {bool fuzzyArrows: true, bool ignoreReturn: false}) =>
       isSubTypeOf(f1, f2);
 
-  bool isBoolType(DartType t) => t == provider.boolType;
-  bool isDoubleType(DartType t) => t == provider.doubleType;
-  bool isIntType(DartType t) => t == provider.intType;
-  bool isNumType(DartType t) => t == provider.numType;
-
-  /// Returns true if this is any kind of object represented by `Number` in JS.
-  ///
-  /// In practice, this is 4 types: num, int, double, and JSNumber.
-  ///
-  /// JSNumber is the type that actually "implements" all numbers, hence it's
-  /// a subtype of int and double (and num). It's in our "dart:_interceptors".
-  bool isNumberInJS(DartType t) => isSubTypeOf(t, provider.numType);
-
-  bool isStringType(DartType t) => t == provider.stringType;
   bool isNonNullableType(DartType t) => false;
   bool maybeNonNullableType(DartType t) => false;