Currently, "sideways casts" -- type errors where one type is assigned
to an unrelated type -- are reported by both ErrorVerifier and strong
mode's Checker. This leads to duplicate errors that the user can see.
ErrorVerifier's errors are generally better: they give the user more
contextual information and are easier to read. So this CL eliminates
Checker's reporting of these errors and only uses ErrorVerifier's.
However, in strong mode, type errors like this are fatal: DDC can't
generate correct code. So this also automatically upgrades all static
type warnings to errors when strong mode is enabled.
R=brianwilkerson@google.com, leafp@google.com
Review URL: https://codereview.chromium.org/1780783002 .
Brian Wilkerson