fix(textarea): update styles due to shadow encapsulation

Author: brandyscarney

core/src/components/textarea/textarea.common.scss

@@ -82,12 +82,12 @@
 // Textarea Within An Item
 // --------------------------------------------------
 
-:host-context(ion-item) {
+:host(.in-item) {
   align-self: baseline;
 }
 
-:host-context(ion-item)[slot="start"],
-:host-context(ion-item)[slot="end"] {
+:host(.in-item[slot="start"]),
+:host(.in-item[slot="end"]) {
   width: auto;
 }
 
@@ -311,6 +311,8 @@
 
   width: 100%;
   min-height: inherit;
+
+  box-sizing: border-box;
 }
 
 // Textarea Highlight

core/src/components/textarea/textarea.tsx

@@ -854,6 +854,7 @@ export class Textarea implements ComponentInterface {
           [`textarea-shape-${shape}`]: shape !== undefined,
           [`textarea-size-${size}`]: true,
           [`textarea-label-placement-${labelPlacement}`]: true,
+          'in-item': inItem,
           'textarea-disabled': disabled,
           'textarea-readonly': readonly,
         })}