Fixed id parsing.

com.oracle.truffle.r.parser/src/com/oracle/truffle/r/parser/R.g

@@ -577,6 +577,7 @@ DD : '..' ('0'..'9')+ ;
 
 ID
     : '.'* ID_NAME
+    | '.' '.'+ ('0'..'9')* ID_NAME
     | '.'
     | '.' '.'
     | '`' BACKTICK_NAME

com.oracle.truffle.r.test/src/com/oracle/truffle/r/test/library/base/TestSimpleParsing.java

@@ -90,4 +90,12 @@ public class TestSimpleParsing extends TestBase {
         assertEval("setClass('Foo', representation(x='numeric')); a <- new('Foo'); a@x");
         assertEval("setClass('Foo', representation(x='numeric')); a <- new('Foo'); a@'x'");
     }
+
+    @Test
+    public void testId() {
+        assertEval("{ ..7foo <- 42 }");
+        assertEval("{ ...7foo <- 42 }");
+        assertEval("{ ..77foo <- 42 }");
+    }
+
 }