Implement size for URLSearchParams (#51507)

Summary:
The current `URLSearchParams` is missing the readonly `size` property defined in the [whatwg spec](https://url.spec.whatwg.org/#interface-urlsearchparams), and attempting to use it returns `undefined`. This PR adds it.

## Changelog:
[GENERAL] [FIXED] - Added size property to URLSearchParams implementation
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Pull Request resolved: #51507

Test Plan: I've modified the [tests](packages/react-native/Libraries/Blob/__tests__/URL-test.js) to assert the `size` property is correct.

Reviewed By: cipolleschi

Differential Revision: D75205273

Pulled By: rshest

fbshipit-source-id: 4b773dfc95693a5e084663258de50d161d6facff

Author: louix

packages/react-native/Libraries/Blob/URLSearchParams.js

@@ -13,6 +13,10 @@
 export class URLSearchParams {
   _searchParams: Map<string, string[]> = new Map();
 
+  get size(): number {
+    return this._searchParams.size;
+  }
+
   constructor(params?: Record<string, string> | string | [string, string][]) {
     if (params === null) {
       return;

packages/react-native/Libraries/Blob/URLSearchParams.js.flow

@@ -10,6 +10,7 @@
 
 declare export class URLSearchParams {
   _searchParams: Array<[string, string]>;
+  +size: number;
   constructor(
     params?: Record<string, string> | string | Array<[string, string]>,
   ): void;

packages/react-native/Libraries/Blob/__tests__/URL-test.js

@@ -59,6 +59,7 @@ describe('URL', function () {
 
     // Test searchParams
     const searchParams = url.searchParams;
+    expect(searchParams.size).toBe(2);
     expect(searchParams.get('query')).toBe('testQuery');
     expect(searchParams.get('key')).toBe('value');
 
@@ -69,6 +70,7 @@ describe('URL', function () {
         '&param3=value3+with+spaces+legacy',
       ].join(''),
     );
+    expect(paramsFromString.size).toBe(3);
     expect(paramsFromString.get('param1')).toBe('value1');
     expect(paramsFromString.get('param2')).toBe('value2 with spaces');
     expect(paramsFromString.get('param3')).toBe('value3 with spaces legacy');
@@ -82,6 +84,7 @@ describe('URL', function () {
       active: 'true',
     });
 
+    expect(paramsFromObject.size).toBe(3);
     expect(paramsFromObject.get('user')).toBe('john');
     expect(paramsFromObject.get('age')).toBe('30');
     expect(paramsFromObject.get('active')).toBe('true');
@@ -97,6 +100,7 @@ describe('URL', function () {
 
     // URLSearchParams: Empty
     const emptyParams = new URLSearchParams('');
+    expect(emptyParams.size).toBe(0);
     expect([...emptyParams.entries()]).toEqual([]);
 
     // URLSearchParams: Array (for multiple values of the same key)
@@ -105,6 +109,7 @@ describe('URL', function () {
       ['key1', 'value2'],
       ['key2', 'value3'],
     ]);
+    expect(paramsFromArray.size).toBe(2);
     expect(paramsFromArray.getAll('key1')).toEqual(['value1', 'value2']);
     expect(paramsFromArray.get('key2')).toBe('value3');
 
@@ -115,10 +120,12 @@ describe('URL', function () {
 
     // Adding a new param
     urlParams.append('newKey', 'newValue');
+    expect(urlParams.size).toBe(3);
     expect(urlParams.get('newKey')).toBe('newValue');
 
     // Deleting a param
     urlParams.delete('key');
+    expect(urlParams.size).toBe(2);
     expect(urlParams.get('key')).toBeNull();
 
     // Checking if a param exists

packages/react-native/Libraries/__tests__/__snapshots__/public-api-test.js.snap

@@ -1343,6 +1343,7 @@ declare export class URL {
 
 exports[`public API should not change unintentionally Libraries/Blob/URLSearchParams.js.flow 1`] = `
 "declare export class URLSearchParams {
+  +size: number;
   constructor(
     params?: Record<string, string> | string | Array<[string, string]>
   ): void;