[FIX] web: size of text fields textarea when invisible by default

Text fields, or char fields having widget="text",
were not sized correctly when the field was not
visible by default, ans was set visible thanks
to attrs and other fields values.

opw-629394

addons/web/static/src/js/view_form.js

@@ -2647,6 +2647,7 @@ instance.web.form.FieldText = instance.web.form.AbstractField.extend(instance.we
             this.$textarea = this.$el.find('textarea');
             this.auto_sized = false;
             this.default_height = this.$textarea.css('height');
+            if (this.default_height === '0px') this.default_height = '90px';
             if (this.get("effective_readonly")) {
                 this.$textarea.attr('disabled', 'disabled');
             }