Fix microsoft/monaco-editor#552. Correct composition state when focus/blur editor.

src/vs/editor/browser/controller/textAreaInput.ts

@@ -404,6 +404,12 @@ export class TextAreaInput extends Disposable {
 		}
 		this._hasFocus = newHasFocus;
 
+		if (this._isDoingComposition) {
+			// textarea gets focus, so the state should be clean
+			// https://github.com/Microsoft/monaco-editor/issues/552
+			this._isDoingComposition = false;
+		}
+
 		if (this._hasFocus) {
 			if (browser.isEdge) {
 				// Edge has a bug where setting the selection range while the focus event