Revert "Now the date passed to DateTimeFormat is always in UTC"

This reverts commit b5a9b7c.

docs/src/app/components/pages/components/DatePicker/ExampleInternational.js

@@ -57,7 +57,6 @@ const DatePickerExampleInternational = () => (
         day: 'numeric',
         month: 'long',
         year: 'numeric',
-        timeZone: 'UTC',
       }).format}
     />
   </div>

src/DatePicker/CalendarToolbar.js

@@ -1,6 +1,5 @@
 import React, {Component} from 'react';
 import PropTypes from 'prop-types';
-import {dateUTC} from './dateUtils';
 import IconButton from '../IconButton';
 import NavigationChevronLeft from '../svg-icons/navigation/chevron-left';
 import NavigationChevronRight from '../svg-icons/navigation/chevron-right';
@@ -71,8 +70,7 @@ class CalendarToolbar extends Component {
     const dateTimeFormatted = new DateTimeFormat(locale, {
       month: 'long',
       year: 'numeric',
-      timeZone: 'UTC',
-    }).format(dateUTC(displayDate));
+    }).format(displayDate);
 
     return (
       <div style={styles.root}>

src/DatePicker/CalendarYear.js

@@ -50,8 +50,7 @@ class CalendarYear extends Component {
 
       const yearFormated = new DateTimeFormat(locale, {
         year: 'numeric',
-        timeZone: 'UTC',
-      }).format(utils.dateUTC(utils.setYear(selectedDate, year)));
+      }).format(utils.setYear(selectedDate, year));
 
       const yearButton = (
         <YearButton

src/DatePicker/DateDisplay.js

@@ -1,6 +1,5 @@
 import React, {Component} from 'react';
 import PropTypes from 'prop-types';
-import {dateUTC} from './dateUtils';
 import transitions from '../styles/transitions';
 import SlideInTransitionGroup from '../internal/SlideIn';
 
@@ -142,15 +141,13 @@ class DateDisplay extends Component {
 
     const year = new DateTimeFormat(locale, {
       year: 'numeric',
-      timeZone: 'UTC',
-    }).format(dateUTC(selectedDate));
+    }).format(selectedDate);
 
     const dateTime = new DateTimeFormat(locale, {
       month: 'short',
       weekday: 'short',
       day: '2-digit',
-      timeZone: 'UTC',
-    }).format(dateUTC(selectedDate));
+    }).format(selectedDate);
 
     return (
       <div {...other} style={prepareStyles(styles.root, style)}>

src/DatePicker/DatePicker.js

@@ -1,6 +1,6 @@
 import React, {Component} from 'react';
 import PropTypes from 'prop-types';
-import {dateTimeFormat, formatIso, isEqualDate, dateUTC} from './dateUtils';
+import {dateTimeFormat, formatIso, isEqualDate} from './dateUtils';
 import DatePickerDialog from './DatePickerDialog';
 import TextField from '../TextField';
 
@@ -262,8 +262,7 @@ class DatePicker extends Component {
         day: 'numeric',
         month: 'numeric',
         year: 'numeric',
-        timeZone: 'UTC',
-      }).format(dateUTC(date));
+      }).format(date);
     } else {
       return formatIso(date);
     }
@@ -309,7 +308,7 @@ class DatePicker extends Component {
           onTouchTap={this.handleTouchTap}
           ref="input"
           style={textFieldStyle}
-          value={this.state.date ? formatDate(dateUTC(this.state.date)) : ''}
+          value={this.state.date ? formatDate(this.state.date) : ''}
         />
         <DatePickerDialog
           DateTimeFormat={DateTimeFormat}

src/DatePicker/DayButton.js

@@ -1,7 +1,7 @@
 import React, {Component} from 'react';
 import PropTypes from 'prop-types';
 import Transition from '../styles/transitions';
-import {isEqualDate, dateUTC} from './dateUtils';
+import {isEqualDate} from './dateUtils';
 import EnhancedButton from '../internal/EnhancedButton';
 
 function getStyles(props, context, state) {
@@ -129,8 +129,7 @@ class DayButton extends Component {
         <span style={prepareStyles(styles.label)}>
           {new DateTimeFormat(locale, {
             day: 'numeric',
-            timeZone: 'UTC',
-          }).format(dateUTC(date))}
+          }).format(date)}
         </span>
       </EnhancedButton>
     ) : (

src/DatePicker/dateUtils.js

@@ -119,10 +119,10 @@ export function getWeekArray(d, firstDayOfWeek) {
 }
 
 export function localizedWeekday(DateTimeFormat, locale, day, firstDayOfWeek) {
-  const weekdayFormatter = new DateTimeFormat(locale, {weekday: 'narrow', timeZone: 'UTC'});
+  const weekdayFormatter = new DateTimeFormat(locale, {weekday: 'narrow'});
   const firstDayDate = getFirstDayOfWeek();
 
-  return weekdayFormatter.format(dateUTC(addDays(firstDayDate, day + firstDayOfWeek)));
+  return weekdayFormatter.format(addDays(firstDayDate, day + firstDayOfWeek));
 }
 
 // Convert date to ISO 8601 (YYYY-MM-DD) date string, accounting for current timezone
@@ -168,10 +168,6 @@ export function yearDiff(d1, d2) {
   return ~~(monthDiff(d1, d2) / 12);
 }
 
-export function dateUTC(date) {
-  return new Date(Date.UTC(date.getFullYear(), date.getMonth(), date.getDate()));
-}
-
 export const defaultUtils = {
   getYear,
   setYear,
@@ -181,5 +177,4 @@ export const defaultUtils = {
   getFirstDayOfMonth,
   getWeekArray,
   monthDiff,
-  dateUTC,
 };