Fix some bad documentation links.

sdk/lib/core/num.dart

Index: sdk/lib/core/num.dart
diff --git a/sdk/lib/core/num.dart b/sdk/lib/core/num.dart
index 1db2508433c61630cbf15a8fd990cfa702a1b6d0..56cec4b966852f6b0dada244e754c11e382d0ca8 100644
--- a/sdk/lib/core/num.dart
+++ b/sdk/lib/core/num.dart
@@ -416,7 +416,7 @@ abstract class num implements Comparable<num> {
    * exponential representation (see [toStringAsExponential]).
    *
    * Returns `"NaN"` for [double.NAN], `"Infinity"` for [double.INFINITY], and
-   * `"-Infinity"` for [double.MINUS_INFINITY].
+   * `"-Infinity"` for [double.NEGATIVE_INFINITY].
    *
    * An [int] is converted to a decimal representation with no decimal point.
    *