I have trouble reading the score in m.6 : If the time signature is still 3/4 there, what is it supposed to be in m.7 (no change indicated, but how on earth can m.7 still be 3/4)?
The notes in bar 7 are grace notes. There is a "counted" quarter note rest, and the grace notes (and the final 16th rest) occupy beats 2 and 3 of the bar.
Taking the note durations literally, the bar would be a 16th-note short, but the piece isn't meant to be played in strict tempo!
These groups of notes are (unmarked) tuplets.
In particular, in bar six there is a septuplet (7-in-1), and in bar seven it's a 10-tuplet (deca-tuplet? I wouldn't know of a name for this). The septuplet is also noticable from the fact the the single eight note, the f, in the first beat of bar six is slightly offset from the d-flat: it should be played just before that d-flat, exactly on the 1/2 count.
In non-beginners music, tuplets such as these are often implicit: it's assumed the reader counts the number of notes and deduces the correct timing. Thus, there is no "tuplet bar" underneath the notes. I assume this is to reduce clutter, visual noise. You might come across a different edition that would have these bars, but I expect that Ravel never notated them, and generally in such cases, neither would the editor.
The fact that the tuplet bar is missing probably also indicates there is some freedom in the speed of playing the notes, with an ever so slight rubato.
Note how the speed of the sixteenths/32nds increases bit by bit from bar five to bar seven (but keep in mind there is no accelerando notated; any speed increase comes from the tuplets and 32nds). In the mean time, the volume decrease, and there are increasingly higher arpeggios played. To me, that suggests something "fluttering" away into nothingness, leading to the obvious