Upgrade to GWT 2.5.0 RC1

Major Enhancements

* Super Dev Mode, a replacement for Development Mode (experimental)
* The Elemental library (experimental): efficient DOM access and HTML5 API's (experimental)
* New compiler optimizations from Closure
* The fragment merging optimization, for reducing latency in large apps
* Development mode performance and refresh time speedups
* A new accessibility library for setting ARIA roles, states and properties on DOM elements
* UIBinder enhancements for rendering cells and accessing inline styles

Other Fixes and Enhancements

* Significant speedups in development refresh time as a result of generator result caching for the ClientBundle and RPC generators. Addition of a result caching API that generator writers can use (r10412, r10476).
* Drastic improvement in RPC performance in development mode by providing a development-mode-only implementation for RPC.
* Addition of source map support. See this document for more details.
* Reduction of overhead of Java types in compiler output (r10435).
* Addition of CellTableBuilder API, and an API for custom headers and footers in CellTables (r10435, r10581).
* Addition of pre-deserialization type checking to reduce the number of error messages that occur from attempts to invoke an RPC method with type mismatches (r10518).
* DynaTableRF and Validation samples now use Maven instead of ant.
* DateCell now accepts a TimeZone as a constructor arg.
* <ui:with> now supports the nested <ui:attribute> element for setting property values on a provided type (r10675).
* Improvements in reporting of JavaScriptExceptions in development mode to include the method name and arguments.
* Added ability to mock out Messages and CSSResources for better unit testing (r10723, r10768).
* Added SafeHtml support to parts of the GWT user library.
* CssResource @defs now support multiple values (r10667).
* Added option to compile out logging calls below SEVERE and WARN (r10753).
* CLDR data updated to v2.1.
* Added simple and global currency patterns (r10742).
* Update ISO-8601 time format to accept a timezone of a literal "Z" to mean GMT+0 (r10773).
* Various fixes to stabilize the compiler output on null (no change) recompiles. Added the -Dgwt.normalizeTimestamps system property to zero out the date on output jar files to stabilize builds in build systems which rely on content-addressability (r10810).
* Added GWT emulation for Float.intBitsToFloat, Float.floatToIntBits, Double.longBitsToDouble, and Double.doubleToLongBits.
* Added support for typed arrays (r10839).
* Greatly reduce symbol map size by removing already-pruned symbols from the map.
* Allow absolute paths in ui:style's src attribute.
* Request methods that use Collections as parameters in RequestFactory's JSON-RPC mode now properly encode Collections.

Breaking Changes and Other Changes of Note

* Deprecated methods AbsractCellTable.doSelection(Event,Object,int,int), AbstractHasData.onUpdateSelection(), and CellList.doSelection(Event, Object, int) have been removed.
* Major refactoring of IsRenderable API. See r10352 and r10421 for details.
* The LEFT/RIGHT placement of text in SimplePager has been fixed, which may swap it for people who already worked around the issue. See r10907.
* Tree[Item].addItem/insertItem(String html) have been deprecated due to potential XSS issues. Use Tree[Item].addTextItem/insertTextItem(String text) instead.
* @GwtTransient will now work for any annotation that with that simple name (for example, com.foo.GwtTransient). This prevents library writers from having their library depend on the GWT distribution.
* As part of the GWT compilation, an output file mapping full class names to CSS obfuscated names is generated. This is useful for debugging and testing (r10686).
* Client-side JUnit classes are now available as a separate module without having to pull in GWTTestCase (r10689).
* The permutation mapping file is now generated as part of every compile.
* UIBinder.useLazyWidgets is now set to true by default. See r10730 for more details.
* The following dependencies have been updated to the following versions:
        Eclipse JDT 3.4.2_r894
        Guava 10.0.1
        HTMLUnit 2.9
        Apache HTTP Client 4.1.2 (for HTMLUnit)
        Apache Commons Lang 2.6 (for HTMLUnit)
        NekoHTML 1.9.15 (for HTMLUnit)
* json-1.5.jar is now bundled as a part of gwt-dev.jar. streamhtmlparser (rebased) has been removed from gwt-dev.jar and has been bundled as part of gwt-user.jar and gwt-servlet.jar.
* The compiler metrics aspect of the Compile Report has been disabled by default. The compile report results in instability in the Compile Report. To add compiler metrics to the compilation report, use the -XcompilerMetrics flag.
* GWT no longer supports ChromeFrame. The implementation caused more bugs than it solved.
* The compiler.emulatedStack property should no longer be used. compiler.stackMode is what should be used instead.

In addition to the items mentioned above, see for a list of bug fixes and enhancements for 2.5.0 in the GWT issue tracker.
Known Issues

* Clicking in the navigation area (but not on an actual item) of the Showcase sample results in the navigation area going blank.
* Importing samples/Expenses into Eclipse fails with "Main Type Not Specified" dialog.
* Mismatch in symbol map format between SpeedTracer and GWT results in SpeedTracer not being able to deobfuscate stack traces for GWT applications.