They've added:
Cascading Style Sheets (CSS) Advanced Layout
CSS Regions
CSS3 Multi-column Layout
Flexible Box (“Flexbox”) Layout
Grid Alignment
Positioned floats
CSS3 3-D Transforms
CSS3 Animations
CSS3 Gradients
CSS3 Transitions
CSS3 Text
The text-shadow property
Hyphenation
Panning and Zooming
Removal of style sheet limits
Document Object Model (DOM) support
Advanced Hit Testing APIs
CSSOM Floating Point Value support
Media Query Listeners
Pointer and Gesture DOM events
ECMAScript 5 (ES5) support
The strict variant of ECMAScript (“ES5 strict mode”)
F12 Developer Tools (Not available in Metro style apps.)
Improved support for workers
HTML5 support
Asynchronous Script Execution
Application Cache ("AppCache")
Drag and Drop
File API
Forms Validation
Progress and Range Control
History
Parsing
Sandbox
Web Workers
Channel Messaging
Web Sockets
Spellcheck
Indexed Database API ("IndexedDB")
SVGSVG Filter Effects
Web performance APIs
