Fix for iOS11 initial scroll

src/ios/CDVWKWebViewEngine.m

@@ -30,6 +30,60 @@ Licensed to the Apache Software Foundation (ASF) under one
 #define CDV_IONIC_STOP_SCROLL @"stopScroll"
 
 
+@implementation UIScrollView (BugIOS11)
+
+#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 110000
+
++ (void)load {
+    if (@available(iOS 11.0, *)) {
+        static dispatch_once_t onceToken;
+        dispatch_once(&onceToken, ^{
+            Class class = [self class];
+            SEL originalSelector = @selector(init);
+            SEL swizzledSelector = @selector(xxx_init);
+
+            Method originalMethod = class_getInstanceMethod(class, originalSelector);
+            Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
+
+            BOOL didAddMethod =
+            class_addMethod(class,
+                            originalSelector,
+                            method_getImplementation(swizzledMethod),
+                            method_getTypeEncoding(swizzledMethod));
+
+            if (didAddMethod) {
+                class_replaceMethod(class,
+                                    swizzledSelector,
+                                    method_getImplementation(originalMethod),
+                                    method_getTypeEncoding(originalMethod));
+            } else {
+                method_exchangeImplementations(originalMethod, swizzledMethod);
+            }
+        });
+    }
+}
+
+#endif
+
+#pragma mark - Method Swizzling
+
+- (id)xxx_init {
+    id a = [self xxx_init];
+    if (@available(iOS 11.0, *)) {
+        NSArray *stack = [NSThread callStackSymbols];
+        for(NSString *trace in stack) {
+            if([trace containsString:@"WebKit"]) {
+                [a setContentInsetAdjustmentBehavior:UIScrollViewContentInsetAdjustmentNever];
+                break;
+            }
+        }
+    }
+    return a;
+}
+
+@end
+
+
 @interface CDVWKWeakScriptMessageHandler : NSObject <WKScriptMessageHandler>
 
 @property (nonatomic, weak, readonly) id<WKScriptMessageHandler>scriptMessageHandler;