Revert "Roll the engine (#6099)"

This version of the engine crashes on startup.

This reverts commit a426b6b3.

bin/cache/engine.version

-a1f81c88934ce7d07c16c04760578f35126ff04d
+3551e7a48e2e336777b15c7637af92fd7605b6c5

packages/flutter/test/painting/text_style_test.dart

@@ -98,9 +98,9 @@ void main() {
 
     ui.ParagraphStyle ps2 = s2.getParagraphStyle(textAlign: TextAlign.center);
     expect(ps2, equals(new ui.ParagraphStyle(textAlign: TextAlign.center, fontWeight: FontWeight.w800, fontSize: 10.0, lineHeight: 100.0)));
-    expect(ps2.toString(), 'ParagraphStyle(textAlign: TextAlign.center, fontWeight: FontWeight.w800, fontStyle: unspecified, textOverflow: unspecified, fontFamily: unspecified, fontSize: 10.0, lineHeight: 100.0x)');
+    expect(ps2.toString(), 'ParagraphStyle(textAlign: TextAlign.center, fontWeight: FontWeight.w800, fontStyle: unspecified, fontFamily: unspecified, fontSize: 10.0, lineHeight: 100.0x)');
     ui.ParagraphStyle ps5 = s5.getParagraphStyle();
     expect(ps5, equals(new ui.ParagraphStyle(fontWeight: FontWeight.w700, fontSize: 12.0, lineHeight: 123.0)));
-    expect(ps5.toString(), 'ParagraphStyle(textAlign: unspecified, fontWeight: FontWeight.w700, fontStyle: unspecified, textOverflow: unspecified, fontFamily: unspecified, fontSize: 12.0, lineHeight: 123.0x)');
+    expect(ps5.toString(), 'ParagraphStyle(textAlign: unspecified, fontWeight: FontWeight.w700, fontStyle: unspecified, fontFamily: unspecified, fontSize: 12.0, lineHeight: 123.0x)');
   });
 }