RCTTextField was spliited into two classes

Summary:
Motivation:
 * We maintain two different implementation of <TextInput> (multilined and singlelined), this change makes the implementations much similar which will help us to support and improve both of them in the (near) future;
 * We have to have separated RCTView-based container view for (TextField) to support sofisticated bordering and so on;
 * It opens to us possibility to unify UITextView and UITextField subclasses and remove code duplication across RCTTextView and RCTTextField;
 * Making things decoupled in general will allow us to fix existing bugs with events.

Reviewed By: mmmulani

Differential Revision: D5083010

fbshipit-source-id: 2f2d42c2244d2b39256c51480c1f16f4e3947c01

Libraries/Text/RCTTextField.h

@@ -10,15 +10,16 @@
 #import <UIKit/UIKit.h>
 
 #import <React/RCTComponent.h>
+#import <React/RCTView.h>
 
 @class RCTBridge;
+@class RCTUITextField;
 
-@interface RCTTextField : UITextField
+@interface RCTTextField : RCTView
 
 @property (nonatomic, assign) BOOL caretHidden;
 @property (nonatomic, assign) BOOL selectTextOnFocus;
 @property (nonatomic, assign) BOOL blurOnSubmit;
-@property (nonatomic, strong) UIColor *placeholderTextColor;
 @property (nonatomic, assign) NSInteger mostRecentEventCount;
 @property (nonatomic, strong) NSNumber *maxLength;
 @property (nonatomic, assign) UIEdgeInsets reactPaddingInsets;
@@ -26,6 +27,11 @@
 
 @property (nonatomic, copy) RCTDirectEventBlock onSelectionChange;
 
+@property (nonatomic, strong) RCTUITextField *textField;
+
 - (instancetype)initWithBridge:(RCTBridge *)bridge NS_DESIGNATED_INITIALIZER;
 
+- (instancetype)init NS_UNAVAILABLE;
+- (instancetype)initWithFrame:(CGRect)frame NS_UNAVAILABLE;
+
 @end