JVM_IR: delay writes to the source map until generateMethod

`generateMethodNode` should not have any side effects for the output to
be stable under incremental compilation.

jps-plugin/testData/incremental/incrementalJvmCompilerOnly/inlineFunctionSmapStability/a.kt

@@ -0,0 +1,3 @@
+import inline1.*
+
+fun f() = h()

jps-plugin/testData/incremental/incrementalJvmCompilerOnly/inlineFunctionSmapStability/b.kt

@@ -0,0 +1,7 @@
+package inline1
+
+import inline2.*
+
+fun g() = root()
+
+inline fun h() = root()

jps-plugin/testData/incremental/incrementalJvmCompilerOnly/inlineFunctionSmapStability/b.kt.new

@@ -0,0 +1,7 @@
+package inline1
+
+import inline2.*
+
+fun g() = root() + "!"
+
+inline fun h() = root()

jps-plugin/testData/incremental/incrementalJvmCompilerOnly/inlineFunctionSmapStability/build.log

@@ -0,0 +1,6 @@
+================ Step #1 =================
+Compiling files:
+  src/b.kt
+End of files
+Exit code: OK
+------------------------------------------

jps-plugin/testData/incremental/incrementalJvmCompilerOnly/inlineFunctionSmapStability/c.kt

@@ -0,0 +1,3 @@
+package inline2
+
+inline fun root() = "OK"