fix(JSON): same behavior for embedded & placeholder operators

[maxatome]

Now:

td.JSON(`{"foo": $1}`, td.Between(12, 34))
td.JSON(`{"foo": Between($1, $2)}`, 12, 34)

act the same way. Since v1.10.1 rework, the second was not working as
expected.

At the same time:

td.JSON(`{"foo": Between(12, 34, $1)}`, td.BoundsOutIn)

now works as expected. It was rejected before.

[coveralls]

Pull Request Test Coverage Report for Build 1375590300

• 52 of 52 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.0004%) to 99.849%

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Totals
Change from base Build 1279725928:	0.0004%
Covered Lines:	9245
Relevant Lines:	9259

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💛 - Coveralls