SI-8385 make sure $quasiquote$tuple gets reified properly

Previously due to greediness of SyntacticApplied there was a chance that
quasiquote tuple placeholder got reified as its representation rather
than its meaning.

src/compiler/scala/tools/reflect/quasiquotes/Reifiers.scala

@@ -181,6 +181,10 @@ trait Reifiers { self: Quasiquotes =>
         reifyBuildCall(nme.SyntacticForYield, enums, body)
       case SyntacticAssign(lhs, rhs) =>
         reifyBuildCall(nme.SyntacticAssign, lhs, rhs)
+      // rest will always be non-empty due to the fact that every single-parens
+      // application will be reified by reifyTreePlaceholder before it gets here.
+      case SyntacticApplied(id @ Ident(nme.QUASIQUOTE_TUPLE), first :: rest) =>
+        mirrorBuildCall(nme.SyntacticApplied, reifyTreePlaceholder(Apply(id, first)), reify(rest))
       case SyntacticApplied(fun, argss) if argss.nonEmpty =>
         reifyBuildCall(nme.SyntacticApplied, fun, argss)
       case SyntacticTypeApplied(fun, targs) if targs.nonEmpty =>

test/files/scalacheck/quasiquotes/TermConstructionProps.scala

@@ -295,4 +295,12 @@ object TermConstructionProps extends QuasiquoteProperties("term construction") {
     val q"$a = $b = $c = $d = $e = $f = $g = $h = $k = $l" = q"a = b = c = d = e = f = g = h = k = l"
     assert(a ≈ q"a" && b ≈ q"b" && c ≈ q"c" && d ≈ q"d" && e ≈ q"e" && g ≈ q"g" && h ≈ q"h" && k ≈ q"k" && l ≈ q"l")
   }
+
+  property("SI-8385 a") = test {
+    assertEqAst(q"(foo.x = 1)(2)", "(foo.x = 1)(2)")
+  }
+
+  property("SI-8385 b") = test {
+    assertEqAst(q"(() => ())()", "(() => ())()")
+  }
 }