Suppress line breaks before field/slot references

[gibson042]

I found an instance where a line break after the period in specAlias.[[SlotName]] made for confusing reading, making it look like a sentence was ending prematurely. This CSS change suppresses such line breaks by generating a non-copyable word joiner before each field/slot reference.

Before

Note the line break after "[[Block]] is buffer." and before the "[[ArrayBufferByteLengthData]]" that is connected to buffer:

After

Note the line break moving to after "[[Block]] is" and before "buffer.[[ArrayBufferByteLengthData]]", keeping the latter together as a single unit:

[bakkot]

Thanks!