Summary:
Motivation: The JavaScript image component's onLoad callback optionally
accepts dimensions width and height, allowing the parent of the image to
obtain the native size (without an extra bridge call). It was found that
the dimensions passed into this callback on iOS are frequently (0,0),
not the true native dimensions. This change ensures that the image's
dimensions are passed to the callback. (Examination of the initializer
for RCTImageSource, + (RCTImageSource *)RCTImageSource:(id)json,
indicates that not all code paths produce a size other than CGSizeZero.)
Closes https://github.com/facebook/react-native/pull/15116
Differential Revision: D5460979
Pulled By: javache
fbshipit-source-id: 2dca03c3aae974ef70e981039aa6a804b8e128c8