Fix error in Parser.js while parsing small sections
The transclusionContext capturing logic does not need to bother
about currentBlock while working on single sections(such as MT)
In MTClient there is an attempt to build the sourceDoc with the
given HTML. If that HTML does not have a common ancestor(wrapper
tag), parsing will be re-attempted with a wrapper tag. But
the parsing without wrapper was failing since the assumption
about the currentBlock is not met and js error is thrown.
To avoid js error about accessing the attributes, added a check.
Also added tests. The test7-result.* files are empty because
parsing without wrapper tags will not have any results as expected.