Control-Flow: Improve debug text of ReadValueInstruction

compiler/testData/cfg/controlStructures/localAndNonlocalReturnsWithFinally.instructions

@@ -7,7 +7,7 @@ L0:
     magic[FAKE_INITIALIZER](f: (T) -> U) -> <v0>
     w(f|<v0>)
     r(f) -> <v1>
-    r(this) -> <v2>
+    r(this, <this>) -> <v2>
     mark(f(this))
     call(f(this), invoke|<v1>, <v2>) -> <v3>
     ret(*|<v3>) L1

compiler/testData/cfg/controlStructures/localAndNonlocalReturnsWithFinally.values

@@ -4,7 +4,7 @@ fun <T: Any, U> T.let(f: (T) -> U): U = f(this)
           <v0>: {<: (T) -> U}   NEW: magic[FAKE_INITIALIZER](f: (T) -> U) -> <v0>
 f         <v1>: {<: (T) -> U}   NEW: r(f) -> <v1>
 this      <v2>: {<: T}          COPY
-this      <v2>: {<: T}          NEW: r(this) -> <v2>
+this      <v2>: {<: T}          NEW: r(this, <this>) -> <v2>
 f(this)   <v3>: {<: U}          NEW: call(f(this), invoke|<v1>, <v2>) -> <v3>
 =====================
 == bar ==