it appears to have disabled="false", which matches these rules
[md-raised-button].md-primary[disabled], [md-raised-button].md-accent[disabled], [md-raised-button].md-warn[disabled], [md-raised-button][disabled][disabled], [md-fab].md-primary[disabled], [md-fab].md-accent[disabled], [md-fab].md-warn[disabled], [md-fab][disabled][disabled], [md-mini-fab].md-primary[disabled], [md-mini-fab].md-accent[disabled], [md-mini-fab].md-warn[disabled], [md-mini-fab][disabled][disabled]
it shouldn't have disabled attribute at all(should be undefined instead of false).
would make plunker, but it appears to be outdated( @devversion )
