Previously, computed class properties would be evaluated every time a
new instance of the class was created. This means the property name
may have changed between different instances, as well as potential side
effects.
This commit fixes this by storing the computed value in a separate
variable.
* Don't merge test options.
Particularly, I don't want `lodash/merge` to merge my specific plugins
with the general test plugins. It led to odd behavior where I could
enable a loose transform in my specific test, just to have it overridden
by the test fixture's general options.
* Need options
* add transform-class-properties to stage 3, set spec mode to default
* update readme with examples; use `buildUndefinedNode()`; change behavior to always define both static and nonstatic class properties regardless of spec/loose mode; update tests
