Never produce -0 when evaluating expressions (like -"")

Fix for #1085. The major case was already there, but more expressions can result in -0.

test/compress/evaluate.js

@@ -0,0 +1,9 @@
+negative_zero: {
+    options = { evaluate: true }
+    input: {
+        assert.sameValue(-"", -0, '-""');
+    }
+    expect: {
+        assert.sameValue(-"", -0, '-""');
+    }
+}