Use common assertion in ir-tests and proper arithmetic flag

compiler/testData/codegen/box/ir/primitiveNumberComparisons/comparableToDouble.kt

@@ -1,3 +1,6 @@
+// !LANGUAGE: +ProperIeee754Comparisons
+//IGNORE_BACKEND: JS_IR
+
 fun ltDD(x: Comparable<Double>, y: Double) =
     x is Double && x < y
 

compiler/testData/codegen/box/ir/primitiveNumberComparisons/doubleEqeq.kt

@@ -1,3 +1,4 @@
+// !LANGUAGE: +ProperIeee754Comparisons
 fun eqeq(x: Any, y: Any) =
         x is Double && y is Double && x == y
 

compiler/testData/codegen/box/ir/primitiveNumberComparisons/floatEqeq.kt

@@ -1,3 +1,4 @@
+// !LANGUAGE: +ProperIeee754Comparisons
 fun eqeq(x: Any, y: Any) =
         x is Float && y is Float && x == y
 

compiler/testData/codegen/box/ir/primitiveNumberComparisons/mixedNumberTypes.kt

@@ -1,3 +1,4 @@
+// !LANGUAGE: +ProperIeee754Comparisons
 fun ltDI(x: Any, y: Any) =
     x is Double && y is Int && x < y