Fix type parameters indexes of MockClassDescriptor

Exception was thrown during mapping of arguments to parameters in `computeSupertypeProjections`

 #KT-18522 Fixed

compiler/testData/compileKotlinAgainstCustomBinaries/computeSupertypeWithMissingDependency/library/a.kt

@@ -0,0 +1,3 @@
+package a
+
+interface A<T>

compiler/testData/compileKotlinAgainstCustomBinaries/computeSupertypeWithMissingDependency/library/b.kt

@@ -0,0 +1,8 @@
+package b
+
+import a.A
+
+interface B {
+    fun foo(): A<Int>
+    fun bar(): A<String>
+}

compiler/testData/compileKotlinAgainstCustomBinaries/computeSupertypeWithMissingDependency/output.txt

@@ -0,0 +1,10 @@
+compiler/testData/compileKotlinAgainstCustomBinaries/computeSupertypeWithMissingDependency/source.kt:6:5: error: cannot access class 'a.A'. Check your module classpath for missing or conflicting dependencies
+    if (true) {
+    ^
+compiler/testData/compileKotlinAgainstCustomBinaries/computeSupertypeWithMissingDependency/source.kt:7:11: error: cannot access class 'a.A'. Check your module classpath for missing or conflicting dependencies
+        b.foo()
+          ^
+compiler/testData/compileKotlinAgainstCustomBinaries/computeSupertypeWithMissingDependency/source.kt:9:11: error: cannot access class 'a.A'. Check your module classpath for missing or conflicting dependencies
+        b.bar()
+          ^
+COMPILATION_ERROR

compiler/testData/compileKotlinAgainstCustomBinaries/computeSupertypeWithMissingDependency/source.kt

@@ -0,0 +1,11 @@
+package c
+
+import b.B
+
+fun bar(b: B) {
+    if (true) {
+        b.foo()
+    } else {
+        b.bar()
+    }
+}