Fix sourcelevel help message.

Change-Id: I0a516022038296140c0081dcbb9940d6efe2c3a0

dev/core/src/com/google/gwt/dev/util/arg/ArgHandlerSourceLevel.java

diff --git a/dev/core/src/com/google/gwt/dev/util/arg/ArgHandlerSourceLevel.java b/dev/core/src/com/google/gwt/dev/util/arg/ArgHandlerSourceLevel.java
index 17713ac..0b7cbff 100644
--- a/dev/core/src/com/google/gwt/dev/util/arg/ArgHandlerSourceLevel.java
+++ b/dev/core/src/com/google/gwt/dev/util/arg/ArgHandlerSourceLevel.java
@@ -37,8 +37,7 @@
 
   @Override
   public String getPurpose() {
-    return "Specifies Java source level (defaults to " + SourceLevel.JAVA8.getStringValue() + ":"
-        + SourceLevel.DEFAULT_SOURCE_LEVEL + ")";
+    return "Specifies Java source level (defaults to " + SourceLevel.JAVA8.getStringValue() + ")";
   }
 
   @Override
@@ -61,7 +60,8 @@
     SourceLevel level = SourceLevel.fromString(value);
     if (level == null) {
       System.err.println("Source level must be one of [" +
-          Joiner.on(", ").skipNulls().join(AUTO_SELECT, null, (Object[]) SourceLevel.values()) + "].");
+          Joiner.on(", ").skipNulls().join(AUTO_SELECT, null, (Object[]) SourceLevel.values())
+          + "].");
       return false;
     }
     options.setSourceLevel(level);