textDocument/definition finds the last variable declaration instead of the earliest one

[rcjsuen]

FROM node
ARG var=value
ARG var=value2
RUN echo $var
RUN echo $var

If you select the $var on the two RUN lines and invoke the textDocument/definition request, it will jump to the second ARG line. It should jump to the first ARG line instead.

[rcjsuen]

Actually, looks like it finds the last one instead. The textDocument/definition request returns the second ARG instruction at the bottom instead of the first.

FROM node
ARG var
RUN echo $var
ARG var

[rcjsuen]

Fixed by 98601e9. The commit message is wrong and it fixes this issue, not #140.