Revert two Kernel changes that were causing test failures.

pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.dart

Index: pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.dart
index eb98e56e3ff80a12c2e1757d2c9d0fd60c13cc9c..5f9ef6bc0b7d43312d91918d4eaea26311079ea0 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.dart
@@ -502,7 +502,6 @@ class KernelLibraryBuilder
 
   @override
   void addField(
-      String documentationComment,
       List<MetadataBuilder> metadata,
       int modifiers,
       KernelTypeBuilder type,
@@ -512,16 +511,8 @@ class KernelLibraryBuilder
       bool hasInitializer) {
     addBuilder(
         name,
-        new KernelFieldBuilder(
-            documentationComment,
-            metadata,
-            type,
-            name,
-            modifiers,
-            this,
-            charOffset,
-            initializerTokenForInference,
-            hasInitializer),
+        new KernelFieldBuilder(metadata, type, name, modifiers, this,
+            charOffset, initializerTokenForInference, hasInitializer),
         charOffset);
   }
 
@@ -550,7 +541,6 @@ class KernelLibraryBuilder
   }
 
   void addProcedure(
-      String documentationComment,
       List<MetadataBuilder> metadata,
       int modifiers,
       KernelTypeBuilder returnType,
@@ -572,7 +562,6 @@ class KernelLibraryBuilder
     if (constructorName != null) {
       name = constructorName;
       procedure = new KernelConstructorBuilder(
-          documentationComment,
           metadata,
           modifiers & ~abstractMask,
           returnType,
@@ -586,7 +575,6 @@ class KernelLibraryBuilder
           nativeMethodName);
     } else {
       procedure = new KernelProcedureBuilder(
-          documentationComment,
           metadata,
           modifiers,
           returnType,
@@ -608,7 +596,6 @@ class KernelLibraryBuilder
   }
 
   void addFactoryMethod(
-      String documentationComment,
       List<MetadataBuilder> metadata,
       int modifiers,
       ConstructorReferenceBuilder constructorNameReference,
@@ -631,7 +618,6 @@ class KernelLibraryBuilder
     }
     assert(constructorNameReference.suffix == null);
     KernelProcedureBuilder procedure = new KernelProcedureBuilder(
-        documentationComment,
         metadata,
         staticMask | modifiers,
         returnType,