Add isFinite getter to num.

sdk/lib/_internal/lib/js_number.dart

 // Copyright (c) 2012, 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.
 
 part of _interceptors;
 
 /**
  * The super interceptor class for [JSInt] and [JSDouble]. The compiler
  * recognizes this class as an interceptor, and changes references to
  * [:this:] to actually use the receiver of the method, which is
@@ skipping 31 matching lines @@
 
   bool get isNegative => (this == 0) ? (1 / this) < 0 : this < 0;
 
   bool get isNaN => JS('bool', r'isNaN(#)', this);
 
   bool get isInfinite {
     return JS('bool', r'# == Infinity', this)
         || JS('bool', r'# == -Infinity', this);
   }
 
+  bool get isFinite => JS('bool', r'isFinite(#)', this);
+
   num remainder(num b) {
     checkNull(b); // TODO(ngeoffray): This is not specified but co19 tests it.
     if (b is! num) throw new ArgumentError(b);
     return JS('num', r'# % #', this, b);
   }
 
   num abs() => JS('num', r'Math.abs(#)', this);
 
   int toInt() {
     if (isNaN) throw new UnsupportedError('NaN');
@@ skipping 277 matching lines @@
 
   Type get runtimeType => int;
 
   int operator ~() => JS('int', r'(~#) >>> 0', this);
 }
 
 class JSDouble extends JSNumber implements double {
   const JSDouble();
   Type get runtimeType => double;
 }