BREAKING CHANGES

PerfEvents:
- Remove FrameworkLogEvents. EVENT_CREATE_LAYOUT, FrameworkLogEvents. EVENT_CSS_LAYOUT , and FrameworkLogEvents. EVENT_COLLECT_RESULTS: these are replaced by the sub-spans "start_create_layout"/"end_create_layout", "start_measure"/"end_measure", and "start_collect_results"/"end_collect_results" under the existing top-level EVENT_CALCULATE_LAYOUT_STATE event. The PerfEvent#markerPoint API can be used to log these sub-spans (b859605)
- Remove FrameworkLogEvents.PREPARE_MOUNT without replacement: this didn't provide much value (4917370)
- Remove FrameworkLogEvents.DRAW without replacement: this was not free to maintain and didn't provide much value (9e548cb)
Default Range Ratio: The default range ratio for Sections/RecyclerBinder is changed from 4 screens worth of content in either direction to 2. This should improve resource usage with minimal effects on scroll performance. (9b4fe95)
ComponentsSystrace.provide: ComponentsSystrace now assumes an implementation will be provided before any other litho operations occur (457a20f)

Improvements

ComponentsLogger implementations can now return null for event types they don't care about (4075eb7)
Add RecyclerCollectionEventsController#requestScrollBy (0146857)
Preliminary Robolectric v4 support (4c2f657, etc.)
More efficient code generation for state updates in Components and Sections (8c5c7e3, etc.)

Remove usage of API 19+ Objects class in cached value API (aabb24a)
Unset Components scope when creating a new ComponentContext in ComponentTree (05f11a7)
Fix perf logging for dirty mounts (3ad8bfb)
Fix crash when @OnCalculateCachedValue takes no args (2a0f524)
Reduce number of systrace markers in collectResults: these were skewing they perceived size of collectResults in production and weren't actionable (3107467)

See all changes here: v0.26.0...v0.27.0