"invalid property id" with keep comments placement

Test file:

var Foo = {
  /*! keep comment before an object method */
  bar: function() {
    var a = 1;
  }
}

Result:

$ java -jar yuicompressor-2.4.8.jar yui-test.js
[ERROR] in yui-test.js
  3:21:invalid property id
[ERROR] in yui-test.js
  8:1:syntax error
[ERROR] in yui-test.js
  1:0:Compilation produced 2 syntax errors.
org.mozilla.javascript.EvaluatorException: Compilation produced 2 syntax errors.
    at com.yahoo.platform.yui.compressor.YUICompressor$1.runtimeError(YUICompressor.java:172)
    at org.mozilla.javascript.Parser.parse(Parser.java:396)
    at org.mozilla.javascript.Parser.parse(Parser.java:340)
    at com.yahoo.platform.yui.compressor.JavaScriptCompressor.parse(JavaScriptCompressor.java:315)
    at com.yahoo.platform.yui.compressor.JavaScriptCompressor.<init>(JavaScriptCompressor.java:536)
    at com.yahoo.platform.yui.compressor.YUICompressor.main(YUICompressor.java:147)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.yahoo.platform.yui.compressor.Bootstrap.main(Bootstrap.java:21)

However, placing the comment inside the function works as expected.

var Foo = {
  bar: function() {
    /*! keep comment */
    var a = 1;
  }
}

Gives:

$ java -jar yuicompressor-2.4.8.jar yui-test.js
var Foo={bar:function(){
/*! keep comment */
;var b=1}};

Also reproducible with latest on master.

yui / yuicompressor

"invalid property id" with keep comments placement #300