Fixed NullPointerException in handling of Jetty arguments

Bug: #9472
Change-Id: Ib7d3d49f08b73a052b8c3a775d8f5e5121a997a1
Bug-Link: https://github.com/gwtproject/gwt/issues/9472

dev/core/src/com/google/gwt/dev/shell/jetty/JettyLauncher.java

diff --git a/dev/core/src/com/google/gwt/dev/shell/jetty/JettyLauncher.java b/dev/core/src/com/google/gwt/dev/shell/jetty/JettyLauncher.java
index f990610..fcfe5d3 100644
--- a/dev/core/src/com/google/gwt/dev/shell/jetty/JettyLauncher.java
+++ b/dev/core/src/com/google/gwt/dev/shell/jetty/JettyLauncher.java
@@ -655,12 +655,13 @@
           keyStorePassword = value;
         } else if ("pwfile".equals(tag)) {
           useSsl = true;
-          keyStorePassword = Util.readFileAsString(new File(value)).trim();
+          keyStorePassword = Util.readFileAsString(new File(value));
           if (keyStorePassword == null) {
             logger.log(TreeLogger.ERROR,
                 "Unable to read keystore password from '" + value + "'");
             return false;
           }
+          keyStorePassword = keyStorePassword.trim();
         } else if ("clientAuth".equals(tag)) {
           useSsl = true;
           try {