Advance bootstrap to include fix in NI about Nothing-expressions

See 1594c1fc for details. Also, remove fix from f07fed9a.

build.gradle.kts

@@ -10,7 +10,7 @@ import org.gradle.kotlin.dsl.*
 buildscript {
     extra["defaultSnapshotVersion"] = "1.3-SNAPSHOT"
 
-    kotlinBootstrapFrom(BootstrapOption.TeamCity("1.3.40-dev-310", onlySuccessBootstrap = false))
+    kotlinBootstrapFrom(BootstrapOption.TeamCity("1.3.40-dev-431", onlySuccessBootstrap = false))
 
     repositories.withRedirector(project) {
         bootstrapKotlinRepo?.let(::maven)

compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/CoroutineTransformerMethodVisitor.kt

@@ -982,7 +982,7 @@ private fun findSafelyReachableReturns(methodNode: MethodNode, sourceFrames: Arr
         if (!insn.isMeaningful || insn.opcode in SAFE_OPCODES || insn.isInvisibleInDebugVarInsn(methodNode) ||
             isInlineMarker(insn)) {
             setOf()
-        } else null as Set<Int>?
+        } else null
     }
 
     var changed: Boolean