Fix abs() for positive numbers

Author: antonmedv

builtin/builtin_test.go

@@ -15,6 +15,7 @@ var tests = []struct {
 	{`len({foo: 1, bar: 2})`, 2},
 	{`len("hello")`, 5},
 	{`abs(-5)`, 5},
+	{`abs(.5)`, .5},
 	{`abs(-.5)`, .5},
 	{`int(5.5)`, 5},
 	{`int(5)`, 5},

vm/runtime/runtime.go

@@ -431,50 +431,74 @@ func Abs(x interface{}) interface{} {
 	case float32:
 		if x.(float32) < 0 {
 			return -x.(float32)
+		} else {
+			return x
 		}
 	case float64:
 		if x.(float64) < 0 {
 			return -x.(float64)
+		} else {
+			return x
 		}
 	case int:
 		if x.(int) < 0 {
 			return -x.(int)
+		} else {
+			return x
 		}
 	case int8:
 		if x.(int8) < 0 {
 			return -x.(int8)
+		} else {
+			return x
 		}
 	case int16:
 		if x.(int16) < 0 {
 			return -x.(int16)
+		} else {
+			return x
 		}
 	case int32:
 		if x.(int32) < 0 {
 			return -x.(int32)
+		} else {
+			return x
 		}
 	case int64:
 		if x.(int64) < 0 {
 			return -x.(int64)
+		} else {
+			return x
 		}
 	case uint:
 		if x.(uint) < 0 {
 			return -x.(uint)
+		} else {
+			return x
 		}
 	case uint8:
 		if x.(uint8) < 0 {
 			return -x.(uint8)
+		} else {
+			return x
 		}
 	case uint16:
 		if x.(uint16) < 0 {
 			return -x.(uint16)
+		} else {
+			return x
 		}
 	case uint32:
 		if x.(uint32) < 0 {
 			return -x.(uint32)
+		} else {
+			return x
 		}
 	case uint64:
 		if x.(uint64) < 0 {
 			return -x.(uint64)
+		} else {
+			return x
 		}
 	}
 	panic(fmt.Sprintf("invalid argument for abs (type %T)", x))