Don't recreate ProjectResolutionFacade on every completion

Rely on POM events sent when modifying synthetic file copies during
completion to update the OOCB modification count, and recreate
facade only on OOCB mod count changes.

idea/idea-analysis/src/org/jetbrains/kotlin/idea/caches/resolve/KotlinCacheServiceImpl.kt

@@ -182,9 +182,18 @@ class KotlinCacheServiceImpl(val project: Project) : KotlinCacheService {
         val targetPlatform = files.map { TargetPlatformDetector.getPlatform(it) }.toSet().single()
         val syntheticFileModule = files.map(KtFile::getModuleInfo).toSet().single()
         val sdk = syntheticFileModule.sdk
-        val filesModificationTracker = ModificationTracker {
-            // TODO: Check getUserData(FILE_OUT_OF_BLOCK_MODIFICATION_COUNT) actually works
-            files.sumByLong { it.outOfBlockModificationCount + it.modificationStamp }
+        val filesModificationTracker: ModificationTracker
+        // File copies are created during completion and receive correct modification events through POM.
+        // Dummy files created e.g. by J2K do not receive events.
+        if (files.all { it.originalFile != it }) {
+            filesModificationTracker = ModificationTracker {
+                files.sumByLong { it.outOfBlockModificationCount }
+            }
+        }
+        else {
+            filesModificationTracker = ModificationTracker {
+                files.sumByLong { it.outOfBlockModificationCount + it.modificationStamp }
+            }
         }
         val dependenciesForSyntheticFileCache = listOf(PsiModificationTracker.OUT_OF_CODE_BLOCK_MODIFICATION_COUNT, filesModificationTracker)
         val debugName = "completion/highlighting in $syntheticFileModule for files ${files.joinToString { it.name }} for platform $targetPlatform"