[FE] Return Name? instead of List<Name> from getBuiltinFunctionNamesByJvmName

This is much more correct, because we have one to one mapping for
  special java functions in this case, so using single nullable name
  instead of list of names makes code more readable

core/compiler.common.jvm/src/org/jetbrains/kotlin/load/java/SpecialGenericSignatures.kt

@@ -127,13 +127,13 @@ open class SpecialGenericSignatures {
 
         val ORIGINAL_SHORT_NAMES: List<Name> = NAME_AND_SIGNATURE_TO_JVM_REPRESENTATION_NAME_MAP.keys.map { it.name }
 
-        val JVM_SHORT_NAME_TO_BUILTIN_SHORT_NAMES_MAP: Map<Name, List<Name>> =
+        val JVM_SHORT_NAME_TO_BUILTIN_SHORT_NAMES_MAP: Map<Name, Name> =
             NAME_AND_SIGNATURE_TO_JVM_REPRESENTATION_NAME_MAP.entries
                 .map { Pair(it.key.name, it.value) }
-                .groupBy({ it.second }, { it.first })
+                .associateBy({ it.second }, { it.first })
 
-        fun getBuiltinFunctionNamesByJvmName(name: Name): List<Name> =
-            JVM_SHORT_NAME_TO_BUILTIN_SHORT_NAMES_MAP[name] ?: emptyList()
+        fun getBuiltinFunctionNamesByJvmName(name: Name): Name? =
+            JVM_SHORT_NAME_TO_BUILTIN_SHORT_NAMES_MAP[name]
 
         val Name.sameAsBuiltinMethodWithErasedValueParameters: Boolean
             get() = this in ERASED_VALUE_PARAMETERS_SHORT_NAMES