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, 20 insertions, 0 deletions

diff --git a/src/source-error-handler.h b/src/source-error-handler.h
index eaa50300..7cac7fca 100644
--- a/src/source-error-handler.h
+++ b/src/source-error-handler.h
@@ -86,6 +86,26 @@ class SourceErrorHandlerFile : public SourceErrorHandler {
   size_t source_line_max_length_;
 };
 
+class SourceErrorHandlerBuffer : public SourceErrorHandler {
+ public:
+  explicit SourceErrorHandlerBuffer(size_t source_line_max_length = 80);
+
+  bool OnError(const Location*,
+               const std::string& error,
+               const std::string& source_line,
+               size_t source_line_column_offset) override;
+
+  size_t source_line_max_length() const override {
+    return source_line_max_length_;
+  }
+
+  const std::string& buffer() const { return buffer_; }
+
+ private:
+  size_t source_line_max_length_;
+  std::string buffer_;
+};
+
 }  // namespace wabt
 
 #endif // WABT_SOURCE_ERROR_HANDLER_H_