tests: Add avm2/edittext_scrollh test

This test verifies the behavior of setting TextField.scrollH.

tests/tests/swfs/avm2/edittext_scrollh/Test.as

@@ -0,0 +1,39 @@
+package {
+import flash.display.Sprite;
+import flash.text.TextField;
+import flash.text.TextFormat;
+
+public class Test extends Sprite {
+    public function Test() {
+        stage.scaleMode = "noScale";
+        var text = new TextField();
+        text.width = 20;
+        text.height = 20;
+        addChild(text);
+
+        trace(text.scrollH);
+        text.scrollH = 1;
+        trace(text.scrollH);
+        text.scrollH = -1;
+        trace(text.scrollH);
+
+        text.text = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
+
+        text.scrollH = 10;
+        trace(text.scrollH);
+        text.scrollH = 5;
+        trace(text.scrollH);
+        text.scrollH = -15;
+        trace(text.scrollH);
+        text.scrollH = -1;
+        trace(text.scrollH);
+        text.scrollH = 0;
+        trace(text.scrollH);
+
+        text.scrollH = 1.23;
+        trace(text.scrollH);
+        text.scrollH = 3.93;
+        trace(text.scrollH);
+    }
+}
+}

tests/tests/swfs/avm2/edittext_scrollh/output.txt

@@ -0,0 +1,10 @@
+0
+0
+0
+10
+5
+15
+1
+0
+1
+3

tests/tests/swfs/avm2/edittext_scrollh/test.toml

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+num_ticks = 1