Add tests for distinct operations

idea/testData/debugger/sequence/exec/sequence/outs/distinct.out

@@ -0,0 +1,39 @@
+LineBreakpoint created at Distinct.kt:5
+Run Java
+Connected to the target VM
+Distinct.kt:5
+listOf(1, 2, 3, 2, 1, 3, 4, 2).asSequence()
+.distinct()
+.count()
+distinct
+    before: 1,3,5,7,8,9,10,12
+    after: 2,4,6,11
+count
+    before: 2,4,6,11
+    after: nothing
+mappings for distinct
+  direct:
+    1 -> 2
+    3 -> 4
+    5 -> 6
+    7 -> 4
+    8 -> 2
+    9 -> 6
+    10 -> 11
+    12 -> 4
+  reverse:
+    1,8 <- 2
+    3,7,12 <- 4
+    5,9 <- 6
+    10 <- 11
+mappings for count
+  direct:
+    2 -> nothing
+    4 -> nothing
+    6 -> nothing
+    11 -> nothing
+  reverse:
+    empty
+Disconnected from the target VM
+
+Process finished with exit code 0

idea/testData/debugger/sequence/exec/sequence/outs/distinctBy.out

@@ -0,0 +1,10 @@
+LineBreakpoint created at DistinctBy.kt:5
+Run Java
+Connected to the target VM
+DistinctBy.kt:5
+Exception caught: junit.framework.AssertionFailedError: Unresolved reference: andThen, Unresolved reference: andThen
+Disconnected from the target VM
+
+WRONG! Should be fixed in the platform
+
+Process finished with exit code 0

idea/testData/debugger/sequence/exec/sequence/outs/distinctObjects.out

@@ -0,0 +1,34 @@
+LineBreakpoint created at DistinctObjects.kt:6
+Run Java
+Connected to the target VM
+DistinctObjects.kt:6
+listOf(str('a'), str('b'), str('a'), str('c'), str('b')).asSequence()
+.distinct()
+.count()
+distinct
+    before: 1,3,5,6,8
+    after: 2,4,7
+count
+    before: 2,4,7
+    after: nothing
+mappings for distinct
+  direct:
+    1 -> 2
+    3 -> 4
+    5 -> 2
+    6 -> 7
+    8 -> 4
+  reverse:
+    1,5 <- 2
+    3,8 <- 4
+    6 <- 7
+mappings for count
+  direct:
+    2 -> nothing
+    4 -> nothing
+    7 -> nothing
+  reverse:
+    empty
+Disconnected from the target VM
+
+Process finished with exit code 0

idea/testData/debugger/sequence/exec/sequence/src/distinct/Distinct.kt

@@ -0,0 +1,6 @@
+package distinct
+
+fun main(args: Array<String>) {
+  // Breakpoint!
+  listOf(1, 2, 3, 2, 1, 3, 4, 2).asSequence().distinct().count()
+}

idea/testData/debugger/sequence/exec/sequence/src/distinct/DistinctBy.kt

@@ -0,0 +1,6 @@
+package distinct
+
+fun main(args: Array<String>) {
+  // Breakpoint!
+  listOf(3, 4, 234, 34, 54, 23, 4, 23, 543, 5, 46).asSequence().distinctBy { it % 10 }.toList()
+}

idea/testData/debugger/sequence/exec/sequence/src/distinct/DistinctObjects.kt

@@ -0,0 +1,7 @@
+package distinct
+
+fun main(args: Array<String>) {
+  fun str(chr: Char): String = String(charArrayOf(chr))
+  // Breakpoint!
+  listOf(str('a'), str('b'), str('a'), str('c'), str('b')).asSequence().distinct().count()
+}