feat(turbopack): Evaluate simple numeric addition (vercel#70273)

### What?

Add evaluation logic for cases where we are sure that the result is a
number and not a string.

### Why?

It's required for DCE.

turbopack/crates/turbopack-ecmascript/src/analyzer/builtin.rs

@@ -97,6 +97,19 @@ pub fn early_replace_builtin(value: &mut JsValue) -> bool {
 /// processed.
 pub fn replace_builtin(value: &mut JsValue) -> bool {
     match value {
+        JsValue::Add(_, list) => {
+            // numeric addition
+            let mut sum = 0f64;
+            for arg in list {
+                let JsValue::Constant(ConstantValue::Num(num)) = arg else {
+                    return false;
+                };
+                sum += num.0;
+            }
+            *value = JsValue::Constant(ConstantValue::Num(ConstantNumber(sum)));
+            true
+        }
+
         // matching property access like `obj.prop`
         // Accessing a property on something can be handled in some cases
         JsValue::Member(_, box ref mut obj, ref mut prop) => match obj {

turbopack/crates/turbopack-ecmascript/tests/analyzer/graph/nested-args/resolved-explained.snapshot

@@ -29,7 +29,7 @@ v1 = (???*0* + 2)
   ⚠️  function calls are not analysed yet
 
 v2 = (undefined | 2 | (???*0* + 1))
-- *0* (...) => (undefined | a | (r((a + 1)) + 1))((2 + 1))
+- *0* (...) => (undefined | a | (r((a + 1)) + 1))(3)
   ⚠️  recursive function call
   ⚠️  This value might have side effects
 

turbopack/crates/turbopack-tests/tests/execution/turbopack/basic/comptime/input/index.js

@@ -166,3 +166,9 @@ it("should keep side-effects in if statements", () => {
     expect(ok).toBe(2);
   }
 });
+
+it('should analyze numeric additions',()=>{
+  if (1 +2 !==3) {
+    require("fail");
+  }
+})