Sync frida-gum typings with Frida 12.6.14 (#37574)

Also fix some bugs in the existing typings, and bump the major version
to avoid breaking existing consumers that rely on these bugs.

Changelog at:

    https://www.frida.re/news/2019/05/28/frida-12-6-released/

types/frida-gum/index.d.ts

@@ -1,4 +1,4 @@
-// Type definitions for non-npm package frida-gum 13.1
+// Type definitions for non-npm package frida-gum 14.0
 // Project: https://github.com/frida/frida
 // Definitions by: Ole André Vadla Ravnås <https://github.com/oleavr>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
@@ -1525,9 +1525,11 @@ interface UnixSystemFunctionResult {
 }
 
 declare class NativeCallback extends NativePointer {
-    constructor(func: AnyFunction, retType: NativeType, argTypes: NativeType[]);
+    constructor(func: NativeCallbackImplementation, retType: NativeType, argTypes: NativeType[]);
 }
 
+type NativeCallbackImplementation = (this: InvocationContext | undefined, ...params: any[]) => any;
+
 type NativeArgumentValue = NativePointerValue | UInt64 | Int64 | number | boolean | any[];
 
 type NativeReturnValue = NativePointer | UInt64 | Int64 | number | boolean | any[];
@@ -2667,24 +2669,24 @@ declare class DebugSymbol {
     address: NativePointer;
 
     /**
-     * Name of the symbol.
+     * Name of the symbol, or `null` if unknown.
      */
-    name: string;
+    name: string | null;
 
     /**
-     * Module name owning this symbol.
+     * Module name owning this symbol, or `null` if unknown.
      */
-    moduleName: string;
+    moduleName: string | null;
 
     /**
-     * File name owning this symbol.
+     * File name owning this symbol, or `null` if unknown.
      */
-    fileName: string;
+    fileName: string | null;
 
     /**
-     * Line number in `fileName`.
+     * Line number in `fileName`, or `null` if unknown.
      */
-    lineNumber: number;
+    lineNumber: number | null;
 
     /**
      * Looks up debug information for `address`.
@@ -3375,7 +3377,7 @@ declare namespace ObjC {
          *
          * You may replace it by assigning to this property. See `ObjC.implement()` for details.
          */
-        implementation: AnyFunction | NativePointer;
+        implementation: NativePointer;
 
         /**
          * Return type name.
@@ -3980,6 +3982,11 @@ declare namespace Java {
          */
         $className: string;
 
+        /**
+         * Instance used for chaining up to super-class method implementations.
+         */
+        $super: Wrapper;
+
         /**
          * Methods and fields.
          */
@@ -4025,9 +4032,11 @@ declare namespace Java {
         handle: NativePointer;
 
         /**
-         * Implementation. Assign to this property to replace it.
+         * Implementation. Assign a new implementation to this property to
+         * replace the original implementation. Assign `null` at a future point
+         * to revert back to the original implementation.
          */
-        implementation: (...params: any[]) => any;
+        implementation: MethodImplementation | null;
 
         /**
          * Method return type.
@@ -4045,6 +4054,8 @@ declare namespace Java {
         canInvokeWith: (...args: any[]) => boolean;
     }
 
+    type MethodImplementation = (this: Wrapper, ...params: any[]) => any;
+
     interface Field {
         /**
          * Current value of this field. Assign to update the field's value.
@@ -4150,16 +4161,28 @@ declare namespace Java {
          */
         name: string;
 
+        /**
+         * Super-class. Omit to inherit from `java.lang.Object`.
+         */
+        superClass?: Wrapper;
+
         /**
          * Interfaces implemented by this class.
          */
         implements?: Wrapper[];
 
         /**
-         * Methods to implement.
+         * Name and type of each field to expose.
+         */
+        fields?: {
+            [name: string]: string;
+        };
+
+        /**
+         * Methods to implement. Use the special name `$init` to define one or more constructors.
          */
         methods?: {
-            [name: string]: AnyFunction | MethodSpec | MethodSpec[];
+            [name: string]: MethodImplementation | MethodSpec | MethodSpec[];
         };
     }
 
@@ -4177,7 +4200,7 @@ declare namespace Java {
         /**
          * Implementation.
          */
-        implementation: AnyFunction;
+        implementation: MethodImplementation;
     }
 
     interface VM {