Eliminated the redundant ForLoopHeader.needsEmptinessCheck property, cast "bound" to progression type if necessary, fixed variable declaration order.

compiler/testData/codegen/bytecodeText/forLoop/forInUntil.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun test(): Int {
     var sum = 0
     for (i in 1 until 6) {
@@ -12,4 +11,4 @@ fun test(): Int {
 // 0 getEnd
 // 0 getFirst
 // 0 getLast
-// 1 IF
+// 0 getStep

compiler/testData/codegen/bytecodeText/forLoop/primitiveRange.kt

@@ -7,5 +7,4 @@ fun f(r: IntRange) {
 // 0 getStart
 // 0 getEnd
 // 1 getFirst
-// 1 getLast
-// 1 getStep
+// 1 getLast