Auto merge of #12388 - kilobtye:textarea2, r=pcwalton

Let textarea wrap lines

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1. Change textarea's style from white-space: pre to white-space: pre-wrap.
2. Display insertion point when a line is wrapped.

---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #10053 (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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components/style/properties/properties.mako.rs

@@ -2146,10 +2146,6 @@ pub fn modify_style_for_input_text(style: &mut Arc<ComputedValues>) {
     margin_style.margin_right = computed::LengthOrPercentageOrAuto::Length(Au(0));
     margin_style.margin_bottom = computed::LengthOrPercentageOrAuto::Length(Au(0));
     margin_style.margin_left = computed::LengthOrPercentageOrAuto::Length(Au(0));
-
-    // whitespace inside text input should not be collapsed
-    let inherited_text = Arc::make_mut(&mut style.inheritedtext);
-    inherited_text.white_space = longhands::white_space::computed_value::T::pre;
 }
 
 /// Adjusts the `clip` property so that an inline absolute hypothetical fragment doesn't clip its