Single line TextInput fixes (#1284)

Author: christophpurrer

Libraries/Text/TextInput/Singleline/RCTSinglelineTextInputView.m

@@ -28,6 +28,10 @@ - (instancetype)initWithBridge:(RCTBridge *)bridge
 
     _backedTextInputView = [[RCTUITextField alloc] initWithFrame:self.bounds];
     _backedTextInputView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
+#if TARGET_OS_OSX // [TODO(macOS GH#774)
+    _backedTextInputView.cell.scrollable = YES;
+    _backedTextInputView.cell.usesSingleLineMode = YES;
+#endif // ]TODO(macOS GH#774)
     _backedTextInputView.textInputDelegate = self;
 
     [self addSubview:_backedTextInputView];