Set proper origin for cascaded if expression

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/BranchingExpressionGenerator.kt

@@ -81,7 +81,7 @@ class BranchingExpressionGenerator(statementGenerator: StatementGenerator) : Sta
             }
         }
 
-        val irWhen = IrWhenImpl(ktIf.startOffsetSkippingComments, ktIf.endOffset, resultType, IrStatementOrigin.WHEN)
+        val irWhen = IrWhenImpl(ktIf.startOffsetSkippingComments, ktIf.endOffset, resultType, IrStatementOrigin.IF)
 
         irWhen.branches.addAll(irBranches)
 

compiler/testData/ir/irCfg/when/cascadeIf.txt

@@ -3,7 +3,7 @@
 BB 0
 CONTENT
       1 FUN name:compare visibility:public modality:FINAL <> (x:kotlin.Int, y:kotlin.Int) returnType:kotlin.Int flags:
-      2 WHEN type=kotlin.Int origin=WHEN
+      2 WHEN type=kotlin.Int origin=IF
       3 GET_VAR 'value-parameter x: Int' type=kotlin.Int origin=null
       4 GET_VAR 'value-parameter y: Int' type=kotlin.Int origin=null
 OUTGOING -> BB 1, 3
@@ -28,24 +28,24 @@ INCOMING <- BB 0
 CONTENT
       1 CONST Int type=kotlin.Int value=1
 OUTGOING -> BB 6
-    When exit: WHEN type=kotlin.Int origin=WHEN
+    When exit: WHEN type=kotlin.Int origin=IF
 BB 4
 INCOMING <- BB 1
     CALL 'less(Int, Int): Boolean' type=kotlin.Boolean origin=LT
 CONTENT
       1 CONST Int type=kotlin.Int value=-1
 OUTGOING -> BB 6
-    When exit: WHEN type=kotlin.Int origin=WHEN
+    When exit: WHEN type=kotlin.Int origin=IF
 BB 5
 INCOMING <- BB 2
     CONST Boolean type=kotlin.Boolean value=true
 CONTENT
       1 CONST Int type=kotlin.Int value=0
 OUTGOING -> BB 6
-    When exit: WHEN type=kotlin.Int origin=WHEN
+    When exit: WHEN type=kotlin.Int origin=IF
 BB 6
 INCOMING <- BB 3, 4, 5
-    When exit: WHEN type=kotlin.Int origin=WHEN
+    When exit: WHEN type=kotlin.Int origin=IF
 CONTENT
       1 RETURN type=kotlin.Nothing from='compare(Int, Int): Int'
 OUTGOING -> NONE

compiler/testData/ir/irText/expressions/ifElseIf.txt

@@ -3,7 +3,7 @@ FILE fqName:<root> fileName:/ifElseIf.kt
     VALUE_PARAMETER name:i index:0 type:kotlin.Int flags:
     BLOCK_BODY
       RETURN type=kotlin.Nothing from='test(Int): Int'
-        WHEN type=kotlin.Int origin=WHEN
+        WHEN type=kotlin.Int origin=IF
           BRANCH
             if: CALL 'greater(Int, Int): Boolean' type=kotlin.Boolean origin=GT
               arg0: GET_VAR 'value-parameter i: Int' type=kotlin.Int origin=null