Fix formatOnSave by try reading the content from memory first

Author: kkkiio

server/src/main/kotlin/org/javacs/kt/KotlinTextDocumentService.kt

@@ -61,7 +61,10 @@ class KotlinTextDocumentService(
         get() = uri.endsWith(".kts")
 
     private val TextDocumentIdentifier.content: String
-        get() = uriContentProvider.contentOf(parseURI(uri))
+        get() {
+            val uri = parseURI(uri)
+            return sf.contentOfTracked(uri) ?: uriContentProvider.contentOf(uri)
+        }
 
     fun connect(client: LanguageClient) {
         this.client = client

server/src/main/kotlin/org/javacs/kt/SourceFiles.kt

@@ -113,6 +113,10 @@ class SourceFiles(
         }
     }
 
+    fun contentOfTracked(uri: URI):String? {
+        return files[uri]?.content
+    }
+
     fun createdOnDisk(uri: URI) {
         changedOnDisk(uri)
     }