React Native now leaves the original object accessible when it "polyfills" objects. So we check for that, but still have the previous logic in place in case they change their minds.
Rather than using Object.preventExtensions to throw exceptions when setting any out-of-bounds index, we must instead compromise by only throwing for the common cases, which are -1 and list.length. Having Object.keys() support is essential for List to work with React Native ListViewDataSource.
Resolves#80
Optional values are not automatically migrated to required columns since it is a lossy process.
This test case revealed an issue where the number of objects can be lost if all properties of an
object were optional and are all being migrated to required. This happens because the migration
process removes the optional columns in a first pass, and recreates them as required in a second
pass. Since this results in all columns being removed, we lose track of how many objects were
stored. We avoid this by detecting the case where we are about to remove the last column and
inserting a placeholder column that we'll remove after inserting the new columns.
Required columns are migrated to optional by creating a new nullable column,
copying the data from the required column to the optional column, then removing
the original required column.
Added a session ID, that actually tracks the Realm constructor in our RPC server's JS context. This conveniently let us remove the special casing for defaultPath as well as letting us call the Realm constructor with JSObjectCallAsConstructor.
Fixes#68
Since notifications are called synchronously after a write, we fake it by calling them manually for now. The future plan will be more involved, so some of that is stubbed out.