[MERGE #4754 @jackhorton] OS#16115338 Update _.floor to normalize -0 …

…to 0 [OSS-Fuzz]

Merge pull request #4754 from jackhorton:os16115338

The intl spec refers to the `floor` function in [DefaultNumberOption](https://tc39.github.io/ecma402/#sec-defaultnumberoption), which we had previously implemented as exactly Math.floor Math.floor is defined to return -0 when given -0 as input. However, DefaultNumberOption actually refers to [the floor mathematical operation](https://tc39.github.io/ecma262/#sec-mathematical-operations), which states that -0 should be normalized to 0, which is the more intuitive behavior.

This fixes a FailFast that triggered when we couldn't retrieve the minimumFractionDigits as a TaggedInt.

lib/Runtime/Library/InJavascript/Intl.js

@@ -142,7 +142,8 @@
         setPrototypeOf(target, proto = null) { return platform.builtInSetPrototype(target, proto); },
 
         abs: platform.builtInMathAbs,
-        floor: platform.builtInMathFloor,
+        // Make _.floor more like ECMA262 #sec-mathematical-operations' floor by normalizing -0
+        floor(x) { return x === 0 ? 0 : platform.builtInMathFloor(x) },
         max: platform.builtInMathMax,
         pow: platform.builtInMathPow,
 

test/Intl/NumberFormat.js

@@ -149,6 +149,18 @@ const tests = [
             assert.matches(/1[\x20\u00a0]?%/, format({ style: "percent" }, 0.01));
             assert.matches(/10,000[\x20\u00a0]?%/,format({ style: "percent" }, 100));
         }
+    },
+    {
+        name: "Negative 0",
+        body() {
+            assert.areEqual(
+                0,
+                new Intl.NumberFormat(undefined, { minimumFractionDigits: -0 }).resolvedOptions().minimumFractionDigits,
+                "Passing -0 for minimumFractionDigits should get normalized to 0 by DefaultNumberOption"
+            );
+            // This assert may need to change in the future, pending any decision made on https://github.com/tc39/ecma402/issues/219
+            assert.areEqual("0", (-0).toLocaleString(), "-0 should be formatted as 0");
+        }
     }
 ];