Fix password settings crash by modifying property attributes of

TableViewTextItem.textColor.

The Canary crashes when a TableViewTextItem configures its cell and
checks its "textColor" property, which is "assign" and might get released
after assigned. This CL fixes it by changing the property's "assign"
attribute to "strong" so that the UIColor object will be retained.

Bug: 910542
Change-Id: I44b6a60c52c5a470e69a44ca6670720446ef084b
Reviewed-on: https://chromium-review.googlesource.com/c/1356585Reviewed-by: Sergio Collazos <sczs@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Yi Su <mrsuyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612716}

ios/chrome/browser/ui/table_view/cells/table_view_text_item.h

@@ -18,7 +18,7 @@
 // UIColor for the cell's textLabel. Default is
 // kTableViewTextLabelColorLightGrey. ChromeTableViewStyler's |cellTitleColor|
 // takes precedence over the default color, but not over |textColor|.
-@property(nonatomic, assign) UIColor* textColor;
+@property(nonatomic, strong) UIColor* textColor;
 
 @property(nonatomic, strong) NSString* text;