Use the text-control auto content size when calculating max-content
width for primitive text input widgets. CSS Sizing treats cyclic
percentage preferred sizes as initial values for non-replaced
max-content contributions, so an `appearance: none` input with
`width: 100%` should contribute its `width: auto` size instead of
collapsing to zero.
Keep the min-content path unchanged so the percentage-sized replaced
element rule can still compress non-button-like input controls for
flex automatic minimum sizing. Add coverage for an inline-flex
control matching the GitHub file search layout.
