Reland "Add writer to emit the AST."

This reverts commit 5e5655155110e121763e3dca13d20c3eda09167e.

Change-Id: I2c3da583090ebef87cc71a743746d741345847c7
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/122782
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
diff --git a/src/tint/CMakeLists.txt b/src/tint/CMakeLists.txt
index 6a8f503..7f23d23 100644
--- a/src/tint/CMakeLists.txt
+++ b/src/tint/CMakeLists.txt
@@ -677,6 +677,15 @@
   )
 endif()
 
+if(${TINT_BUILD_SYNTAX_TREE_WRITER})
+    list(APPEND TINT_LIB_SRCS
+      writer/syntax_tree/generator.cc
+      writer/syntax_tree/generator.h
+      writer/syntax_tree/generator_impl.cc
+      writer/syntax_tree/generator_impl.h
+    )
+endif()
+
 if(${TINT_BUILD_IR})
   list(APPEND TINT_LIB_SRCS
     ir/binary.cc