[stable] Cherry-pick change to CanvasKit build flags to fix double download (#164341)

## Stable Cherry Pick

Cherry-picks https://github.com/flutter/flutter/pull/162198 to stable to fix issue with double-downloading CanvasKit. 

Fixes https://github.com/flutter/flutter/issues/163250

Impacted Users: All Flutter Web users
Impact Description: `canvaskit.wasm` (a roughly 5 MB download) is double-downloaded. While some browsers may retrieve the second request from the cache, not all do.
Workaround: None
Risk: Low (a small change to the BUILD flags for CanvasKit that prevents `canvaskit.wasm` from being downloaded twice)
Test Coverage: We don't have a test that checks how many requests there are for `canvaskit.wasm`
Validation Steps: Build and run any Flutter Web app and check the network requests to see that `canvaskit.wasm` is only requested once.

CHANGELOG.md

@@ -24,8 +24,11 @@ docs/releases/Hotfix-Documentation-Best-Practices.md
 
 INTERNAL NOTE
 -->
+## Flutter 3.29 Changes
 
-## Flutter 3.29.1 Changes
+### [3.29.2](https://github.com/flutter/flutter/releases/tag/3.29.2)
+
+- [flutter/162198](https://github.com/flutter/flutter/issues/162198) Fixes double-download of canvaskit.wasm
 
 ### [3.29.1](https://github.com/flutter/flutter/releases/tag/3.29.1)
 
@@ -49,8 +52,6 @@ glyphs.
 - [flutter/163261](https://github.com/flutter/flutter/pull/163261) - Fixes for Impeller DrawVertices issues involving snapshots with empty sizes
 - [flutter/163672](https://github.com/flutter/flutter/pull/163672) - Check for tracked engine.version before overriding
 
-## Flutter 3.29 Changes
-
 ### [3.29.0](https://github.com/flutter/flutter/releases/tag/3.29.0)
 Initial stable release.
 

engine/src/build/config/compiler/BUILD.gn

@@ -930,6 +930,14 @@ config("no_optimize") {
       cflags += [ "-fomit-frame-pointer" ]
     }
     ldflags = common_optimize_on_ldflags
+  } else if (is_wasm) {
+    # On WASM we don't want to fully deoptimize the debug build because the
+    # compiled binary will have some functions with too many local variables
+    # and Chrome will reject it.
+    cflags = [
+      "-O1",
+    ]
+    ldflags = common_optimize_on_ldflags
   } else {
     cflags = [ "-O0" ]
   }

engine/src/flutter/skia/modules/canvaskit/BUILD.gn

@@ -62,8 +62,7 @@ canvaskit_wasm_lib("canvaskit") {
   ldflags = []
   if (is_debug) {
     ldflags += [
-      "-O0",
-      "-sDEMANGLE_SUPPORT=1",
+      "-O1",
       "-sASSERTIONS=1",
       "-sGL_ASSERTIONS=1",
       "-g3",
@@ -111,14 +110,14 @@ canvaskit_wasm_lib("canvaskit") {
     "--bind",
     "--no-entry",
     "--pre-js",
+    rebase_path("$_skia_root/modules/canvaskit/util.js"),
+    "--pre-js",
     rebase_path("$_skia_root/modules/canvaskit/preamble.js"),
     "--pre-js",
     rebase_path("$_skia_root/modules/canvaskit/color.js"),
     "--pre-js",
     rebase_path("$_skia_root/modules/canvaskit/memory.js"),
     "--pre-js",
-    rebase_path("$_skia_root/modules/canvaskit/util.js"),
-    "--pre-js",
     rebase_path("$_skia_root/modules/canvaskit/interface.js"),
   ]
 
@@ -165,7 +164,7 @@ canvaskit_wasm_lib("canvaskit") {
     "-sEXPORT_NAME=CanvasKitInit",
     "-sEXPORTED_FUNCTIONS=[_malloc,_free]",
     "-sEXPORTED_RUNTIME_METHODS=HEAP8,HEAPU8,HEAP16,HEAPU16,HEAP32,HEAPF32,HEAPU32,HEAPF64",
-    "-sINCOMING_MODULE_JS_API=onRuntimeInitialized",
+    "-sINCOMING_MODULE_JS_API=[instantiateWasm,onRuntimeInitialized,noExitRuntime]",
     "-sFORCE_FILESYSTEM=0",
     "-sFILESYSTEM=0",
     "-sMODULARIZE",