Merge pull request microsoft#8412 from alexeagle/master

Include sourcefiles in the WriteFileCallback for .d.ts emit

Author: mhegazy

src/compiler/declarationEmitter.ts

@@ -1753,7 +1753,7 @@ namespace ts {
         if (!emitSkipped) {
             const declarationOutput = emitDeclarationResult.referencesOutput
                 + getDeclarationOutput(emitDeclarationResult.synchronousDeclarationOutput, emitDeclarationResult.moduleElementDeclarationEmitInfo);
-            writeFile(host, emitterDiagnostics, declarationFilePath, declarationOutput, host.getCompilerOptions().emitBOM);
+            writeFile(host, emitterDiagnostics, declarationFilePath, declarationOutput, host.getCompilerOptions().emitBOM, sourceFiles);
         }
         return emitSkipped;