Fix external_debug_info section name

According to the spec, the section name does not start with a dot:
https://yurydelendik.github.io/webassembly-dwarf/#external-DWARF

Change-Id: I4ac205332dd9612fe83c2e6322a98bdae3ffa79d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2249669Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Philip Pfaffe <pfaffe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68389}

src/wasm/module-decoder.cc

@@ -33,7 +33,7 @@ constexpr char kNameString[] = "name";
 constexpr char kSourceMappingURLString[] = "sourceMappingURL";
 constexpr char kCompilationHintsString[] = "compilationHints";
 constexpr char kDebugInfoString[] = ".debug_info";
-constexpr char kExternalDebugInfoString[] = ".external_debug_info";
+constexpr char kExternalDebugInfoString[] = "external_debug_info";
 
 const char* ExternalKindName(ImportExportKindCode kind) {
   switch (kind) {
@@ -448,7 +448,7 @@ class ModuleDecoderImpl : public Decoder {
         // if produced by compiler. Its presence likely means that Wasm was
         // built in a debug mode.
       case kExternalDebugInfoSectionCode:
-        // .external_debug_info is a custom section containing a reference to an
+        // external_debug_info is a custom section containing a reference to an
         // external symbol file.
       case kCompilationHintsSectionCode:
         // TODO(frgossen): report out of place compilation hints section as a

test/inspector/debugger/wasm-scripts.js

@@ -59,7 +59,7 @@ const embeddedDWARFSection = {
 
 // Sample external_debug_info section set to "abc".
 const externalDWARFSection = {
-  name: '.external_debug_info',
+  name: 'external_debug_info',
   value: [3, 97, 98, 99]
 };