Using whitespace wouldn't work anyway, since it would be ambiguous:
.a = x
.b = y
Is that ".a=x;.b=y" or ".a=x.b=y"? Of course the latter is invalid, but the parser would have to look ahead an arbitrary number of tokens to discover that.
Another example would be:
.a = x
.b.some_function()
Is that “.a=x; .b.some_function();” or is it “.a = x.b.some_function()”?