density, histogram: free x-axis scales in facets show full range instead of panel-specific ranges

In ggplot2, when using facets with free scales, each panel shows an independent axis range (regardless of the value of 'trim' parameter):

```
data <- data.frame(
value = c(
rnorm(100, mean=5, sd=2), # Group A: mean=5
rnorm(100, mean=150, sd=20) # Group B: mean=150
),
group = rep(c('A', 'B'), each=100)
)

p <- ggplot(data) + geom_density(aes(value, colour=group), trim=FALSE)
p + facet_wrap(facets='group', ncol=1, scales='free_x')
p
```

In similar situation Lets-Plot shows the full data range across all panels.

```
data = pd.DataFrame({
'value': np.concatenate([
np.random. normal(5, 2, 100), # Group A: mean=5
np.random.normal(150, 20, 100) # Group B: mean=150
]),
'group': np.repeat(['A', 'B'], 100)
})

p = ggplot(data) + geom_density(aes('value', color='group'))
p + facet_wrap(facets='group', scales='free_x')
p
```