ForLoopsLowering: Assume step == 1 for *Range (e.g., IntRange) and

handle accordingly (e.g., do not read `step` property).

compiler/testData/codegen/bytecodeText/forLoop/stepped/stepConstOnNonLiteralProgression.kt

@@ -1,6 +1,6 @@
 // TARGET_BACKEND: JVM_IR
 fun box(): String {
-    val intProgression = 1..7
+    val intProgression = 1..7 step 3  // `step` ensures type is IntProgression, NOT IntRange
     for (i in intProgression step 2) {
     }
 
@@ -15,10 +15,9 @@ fun box(): String {
 // Expected lowered form of loop:
 //
 //   // Additional statements:
-//   val progression = intProgression
-//   val nestedFirst = progression.first
-//   val nestedLast = progression.last
-//   val nestedStep = progression.step
+//   val nestedFirst = intProgression.first
+//   val nestedLast = intProgression.last
+//   val nestedStep = intProgression.step
 //   val maybeNegatedStep = if (nestedStep <= 0) -2 else 2
 //
 //   // Standard form of loop over progression