ignore_malloc_size_of for DomRefCell<TextInput<...>> cites closed issue #7193

[pshaughn]

servo/components/script/dom/htmltextareaelement.rs

Lines 49 to 50 in 5f55cd5

	#[ignore_malloc_size_of = "#7193"]
	textinput: DomRefCell<TextInput<ScriptToConstellationChan>>,

servo/components/script/dom/htmlinputelement.rs

Lines 247 to 248 in 5f55cd5

	#[ignore_malloc_size_of = "#7193"]
	textinput: DomRefCell<TextInput<ScriptToConstellationChan>>,

We actually do need an ignore_malloc_size_of either here or in TextInput, since TextInput<T> holds a T and the T here itself holds an IPCSender. There's just room for a little cleanup to remove a reference to #7193, a closed and only half-relevant issue.