React

• Ensure we're using the latest object-assign, which has protection against a non-spec-compliant native Object.assign. (@zpao in #6681)
• Add a new warning to communicate that props objects passed to createElement must be plain objects. (@richardscarrott in #6134)
• Fix a batching bug resulting in some lifecycle methods incorrectly being called multiple times. (@spicyj in #6650)

React DOM

• Fix regression in custom elements support. (@jscissr in #6570)
• Stop incorrectly warning about using onScroll event handler with server rendering. (@Aweary in #6678)
• Fix grammar in the controlled input warning. (@jakeboone02 in #6657)
• Fix issue preventing <object> nodes from being able to read <param> nodes in IE. (@syranide in #6691)
• Fix issue resulting in crash when using experimental error boundaries with server rendering. (@jimfb in #6694)
• Add additional information to the controlled input warning. (@borisyankov in #6341)

React Perf Add-on

• Completely rewritten to collect data more accurately and to be easier to maintain. (@gaearon in #6647, #6046)

React Native Renderer

• Remove some special cases for platform specific branching. (@sebmarkbage in #6660)
• Remove use of merge utility. (@sebmarkbage in #6634)
• Renamed some modules to better indicate usage (@javache in #6643)