Start cleaning up tests (2/N)

Remove Source{} with ast::Builder::create<>
Use Builder helpers where possible

Change-Id: Ia29fe615ac8975252a34f1252c363109ee382d72
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/35508
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>

src/ast/builder.h

@@ -144,7 +144,7 @@ class TypesBuilder {
   }
 
   /// @param subtype the array element type
-  /// @param n the array size. 0 represents unbounded
+  /// @param n the array size. 0 represents a runtime-array.
   /// @return the tint AST type for a array of size `n` of type `T`
   type::Array* array(type::Type* subtype, uint32_t n) const {
     return mod_->create<type::Array>(subtype, n, ArrayDecorationList{});
@@ -422,7 +422,7 @@ class Builder {
   }
 
   /// @param args the arguments for the array constructor
-  /// @return an `TypeConstructorExpression` of a 4x4 matrix of type
+  /// @return an `TypeConstructorExpression` of an array with element type
   /// `T`, constructed with the values `args`.
   template <typename T, int N = 0, typename... ARGS>
   TypeConstructorExpression* array(ARGS&&... args) {
@@ -430,6 +430,19 @@ class Builder {
         Source{}, ty.array<T, N>(), ExprList(std::forward<ARGS>(args)...));
   }
 
+  /// @param subtype the array element type
+  /// @param n the array size. 0 represents a runtime-array.
+  /// @param args the arguments for the array constructor
+  /// @return an `TypeConstructorExpression` of an array with element type
+  /// `subtype`, constructed with the values `args`.
+  template <typename... ARGS>
+  TypeConstructorExpression* array(type::Type* subtype,
+                                   uint32_t n,
+                                   ARGS&&... args) {
+    return create<TypeConstructorExpression>(
+        Source{}, ty.array(subtype, n), ExprList(std::forward<ARGS>(args)...));
+  }
+
   /// @param name the variable name
   /// @param storage the variable storage class
   /// @param type the variable type