Allow bitwise operations on floats, according to Spec (and Javascript behavior)

builtins.go

@@ -478,15 +478,15 @@ var builtinExponent = liftNumeric(func(f float64) float64 {
 
 func liftBitwise(f func(int64, int64) int64) func(*evaluator, potentialValue, potentialValue) (value, error) {
 	return func(e *evaluator, xp, yp potentialValue) (value, error) {
-		x, err := e.evaluateInt64(xp)
+		x, err := e.evaluateNumber(xp)
 		if err != nil {
 			return nil, err
 		}
-		y, err := e.evaluateInt64(yp)
+		y, err := e.evaluateNumber(yp)
 		if err != nil {
 			return nil, err
 		}
-		return makeDoubleCheck(e, float64(f(x, y)))
+		return makeDoubleCheck(e, float64(f(int64(x.value), int64(y.value))))
 	}
 }
 

evaluator.go

@@ -110,8 +110,6 @@ func (e *evaluator) getInt64(val value) (int64, error) {
 	if err != nil {
 		return 0, err
 	}
-	// We conservatively convert ot int32, so that it can be machine-sized int
-	// on any machine. And it's used only for indexing anyway.
 	intNum := int64(num.value)
 	if float64(intNum) != num.value {
 		return 0, e.Error(fmt.Sprintf("Expected an integer, but got %v", num.value))

testdata/bitwise_and3.golden

@@ -1,10 +1 @@
-RUNTIME ERROR: Expected an integer, but got 1e+30
--------------------------------------------------
-	testdata/bitwise_and3:1:1-10	$
-
-1e30 & 42
-
--------------------------------------------------
-	During evaluation	
-
-
+0