(core) Convert a few widgets to typescript and grainjs.

Summary:
No behavior changes.
Diff includes an intermediate commit with only renames, for easier review.

Test Plan: Existing tests should pass.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D2669

app/client/widgets/NTextBox.ts

@@ -5,7 +5,7 @@ import {cssRow} from 'app/client/ui/RightPanel';
 import {alignmentSelect, makeButtonSelect} from 'app/client/ui2018/buttonSelect';
 import {testId} from 'app/client/ui2018/cssVars';
 import {NewAbstractWidget} from 'app/client/widgets/NewAbstractWidget';
-import {Computed, dom, Observable} from 'grainjs';
+import {dom, DomContents, fromKo, Observable} from 'grainjs';
 
 /**
  * TextBox - The most basic widget for displaying text information.
@@ -18,27 +18,15 @@ export class NTextBox extends NewAbstractWidget {
     super(field);
 
     this.alignment = fromKoSave<string>(this.options.prop('alignment'));
-    const wrap = this.options.prop('wrap');
-
-    this.wrapping = Computed.create(this, (use) => {
-      const w = use(wrap);
-      if (w === null || w === undefined) {
-        // When user has yet to specify a desired wrapping state, GridView and DetailView have
-        // different default states. GridView defaults to wrapping disabled, while DetailView
-        // defaults to wrapping enabled.
-        return (this.field.viewSection().parentKey() === 'record') ? false : true;
-      } else {
-        return w;
-      }
-    });
+    this.wrapping = fromKo(this.field.wrapping);
 
     this.autoDispose(this.wrapping.addListener(() => {
       this.field.viewSection().events.trigger('rowHeightChange');
     }));
   }
 
-  public buildConfigDom() {
-    return dom('div',
+  public buildConfigDom(): DomContents {
+    return [
       cssRow(
         alignmentSelect(this.alignment),
         dom('div', {style: 'margin-left: 8px;'},
@@ -46,7 +34,7 @@ export class NTextBox extends NewAbstractWidget {
           testId('tb-wrap-text')
         )
       )
-    );
+    ];
   }
 
   public buildDom(row: DataRowModel) {