Move RegexFilter to gwt-dev for more code sharing opportunities.

Upcoming jsinterop export filtering flag will use this.

Change-Id: I16b7d0391228667cd562840cd8fcd46d44220a53
diff --git a/user/src/com/google/gwt/util/regexfilter/RegexFilter.java b/dev/core/src/com/google/gwt/util/regexfilter/RegexFilter.java
similarity index 100%
rename from user/src/com/google/gwt/util/regexfilter/RegexFilter.java
rename to dev/core/src/com/google/gwt/util/regexfilter/RegexFilter.java
diff --git a/user/src/com/google/gwt/util/regexfilter/package-info.java b/dev/core/src/com/google/gwt/util/regexfilter/package-info.java
similarity index 100%
rename from user/src/com/google/gwt/util/regexfilter/package-info.java
rename to dev/core/src/com/google/gwt/util/regexfilter/package-info.java