Fix emscripten demo and libwabt.js (#407)

This removes the more complicated emscripten wrapper we used before, in
favor of something that is much simpler.

* Remove the memory init file
* Remove the onInputKey handling in the demo so it doesn't auto-indent
  (it was broken now that we have the flat syntax)
* Simplify emscripten-helpers to provide very simple C-function wrappers
  around the wast2wasm API:

  * wabt_parse_ast
  * wabt_resolve_names_script
  * wabt_validate_script
  * wabt_write_binary_module

  The tricky part is that some functions return multiple values, so
  those are returned as structs as well:

  * WabtParseAstResult
  * WabtWriteBinaryModuleResult

1 files changed, 13 insertions, 0 deletions

diff --git a/src/source-error-handler.cc b/src/source-error-handler.cc
index 32976b77..87074ddc 100644
--- a/src/source-error-handler.cc
+++ b/src/source-error-handler.cc
@@ -82,4 +82,17 @@ void SourceErrorHandlerFile::PrintErrorHeader() {
   fprintf(file_, "  ");
 }
 
+SourceErrorHandlerBuffer::SourceErrorHandlerBuffer(
+    size_t source_line_max_length)
+    : source_line_max_length_(source_line_max_length) {}
+
+bool SourceErrorHandlerBuffer::OnError(const Location* loc,
+                                       const std::string& error,
+                                       const std::string& source_line,
+                                       size_t source_line_column_offset) {
+  buffer_ +=
+      DefaultErrorMessage(loc, error, source_line, source_line_column_offset);
+  return true;
+}
+
 }  // namespace wabt