[vm] Use zone memory allocation in StreamingFlowGraphBuilder::BuildSw…

…itchStatement

Change-Id: Ia01bec5941a3daefd4aed43c5951e9ab44f48d46
Reviewed-on: https://dart-review.googlesource.com/69700
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>

runtime/vm/compiler/frontend/base_flow_graph_builder.h

@@ -44,6 +44,9 @@ class Fragment {
   Fragment& operator<<=(Instruction* next);
 
   Fragment closed();
+
+ private:
+  DISALLOW_ALLOCATION();
 };
 
 Fragment operator+(const Fragment& first, const Fragment& second);

runtime/vm/compiler/frontend/kernel_binary_flowgraph.cc

@@ -4809,8 +4809,8 @@ Fragment StreamingFlowGraphBuilder::BuildSwitchStatement() {
   // of a jump due to:
   //   * `continue case_label`
   //   * `case e1: case e2: body`
-  Fragment* body_fragments = new Fragment[case_count];
-  intptr_t* case_expression_offsets = new intptr_t[case_count];
+  Fragment* body_fragments = Z->Alloc<Fragment>(case_count);
+  intptr_t* case_expression_offsets = Z->Alloc<intptr_t>(case_count);
   int default_case = -1;
 
   for (intptr_t i = 0; i < case_count; ++i) {
@@ -4992,9 +4992,6 @@ Fragment StreamingFlowGraphBuilder::BuildSwitchStatement() {
     // default case.
   }
 
-  delete[] body_fragments;
-  delete[] case_expression_offsets;
-
   SetOffset(end_offset);
   return Fragment(head_instructions.entry, current_instructions.current);
 }