[Web] Always return -1 as body length in HTTPClientWeb.

Body length cannot be reliably retrieved from the web.
Reading the "content-length" value will return a meaningless value when
the response is compressed, as reading will return uncompressed chunks
in any case, resulting in a mismatch between the detected body size and
the actual size returned by repeatedly calling read_response_body_chunk.

Additionally, while "content-length" is considered a safe CORS header,
"content-encoding" is not, so using the "content-encoding" to decide if
"content-length" is meaningful is not an option either.

We simply must accept the fact that browsers are awful when it comes to
networking APIs.

(cherry picked from commit f4713d235a)

platform/web/js/libs/library_godot_fetch.js

@@ -50,22 +50,17 @@ const GodotFetch = {
 				return;
 			}
 			let chunked = false;
-			let bodySize = -1;
 			response.headers.forEach(function (value, header) {
 				const v = value.toLowerCase().trim();
 				const h = header.toLowerCase().trim();
 				if (h === 'transfer-encoding' && v === 'chunked') {
 					chunked = true;
 				}
-				if (h === 'content-length') {
-					bodySize = parseInt(v, 10);
-				}
 			});
 			obj.status = response.status;
 			obj.response = response;
 			obj.reader = response.body.getReader();
 			obj.chunked = chunked;
-			obj.bodySize = bodySize;
 		},
 
 		onerror: function (id, err) {
@@ -87,7 +82,6 @@ const GodotFetch = {
 				reading: false,
 				status: 0,
 				chunks: [],
-				bodySize: -1,
 			};
 			const id = IDHandler.add(obj);
 			const init = {
@@ -224,15 +218,6 @@ const GodotFetch = {
 		return p_buf_size - to_read;
 	},
 
-	godot_js_fetch_body_length_get__sig: 'ii',
-	godot_js_fetch_body_length_get: function (p_id) {
-		const obj = IDHandler.get(p_id);
-		if (!obj || !obj.response) {
-			return -1;
-		}
-		return obj.bodySize;
-	},
-
 	godot_js_fetch_is_chunked__sig: 'ii',
 	godot_js_fetch_is_chunked: function (p_id) {
 		const obj = IDHandler.get(p_id);