use faster github actions runner + add assertions

.github/workflows/build.yml

@@ -155,15 +155,15 @@ jobs:
     strategy:
       matrix:
         include:
-          - runner: windows-2022
+          - runner: windows
             build-type: Release
             arch: amd64
             suffix: ""
-          - runner: windows-2022
+          - runner: windows
             build-type: Debug
             arch: amd64
             suffix: -debug
-    runs-on: windows-2022
+    runs-on: ${{ matrix.runner }}
     timeout-minutes: 90
     steps:
       - name: Install VS2022 BuildTools 17.9.7

Source/WTF/wtf/URL.cpp

@@ -240,15 +240,17 @@ static String decodeEscapeSequencesFromParsedURLForWindowsPath(const std::span<c
         // Fast path: no escape sequences.
         // That also means we don't have to worry about non-ASCII characters.
         // We just need to normalize slashes.
-        size_t lastSlash = 0;
+        size_t lastSlash = input[0] == '/' ? 1 : 0;
         size_t index = WTF::find(input, '/', lastSlash);
         while (index != notFound) {
+            ASSERT(index < length);
             builder.append(input.subspan(lastSlash, index - lastSlash));
             builder.append('\\');
             lastSlash = index + 1;
             index = WTF::find(input, '/', lastSlash);
         }
 
+        ASSERT(lastSlash <= length);
         builder.append(input.subspan(lastSlash));
         return builder.toString();
     }