This test setting suggested values on an input element 
and a textarea element. The dump below should have the "suggested value"
instead of "initial value".
| <input>
|   id="test"
|   type="text"
|   value="initial value"
|   this.value="initial value"
|   <shadow:root>
|     <div>
|       id="placeholder"
|       pseudo="-internal-input-suggested"
|       style="display: block !important; user-select: none !important;"
|       shadow:pseudoId="-internal-input-suggested"
|       "suggested value"
|     <div>
|       "initial value"
| <input>
|   id="month"
|   type="month"
|   this.value=""
|   <shadow:root>
|     <div>
|       pseudo="-internal-datetime-container"
|       style="unicode-bidi: normal;"
|       shadow:pseudoId="-internal-datetime-container"
|       <div>
|         datetimeformat="MMMM yyyy"
|         id="date-time-edit"
|         pseudo="-webkit-datetime-edit"
|         style="unicode-bidi: normal;"
|         shadow:pseudoId="-webkit-datetime-edit"
|         <div>
|           pseudo="-webkit-datetime-edit-fields-wrapper"
|           style="unicode-bidi: normal;"
|           shadow:pseudoId="-webkit-datetime-edit-fields-wrapper"
|           <span>
|             aria-label="Month"
|             aria-placeholder="---------"
|             aria-valuemax="12"
|             aria-valuemin="1"
|             aria-valuenow="1"
|             aria-valuetext="January"
|             pseudo="-webkit-datetime-edit-month-field"
|             role="spinbutton"
|             shadow:pseudoId="-webkit-datetime-edit-month-field"
|             "January"
|           <div>
|             pseudo="-webkit-datetime-edit-text"
|             style="unicode-bidi: normal;"
|             shadow:pseudoId="-webkit-datetime-edit-text"
|             " "
|           <span>
|             aria-label="Year"
|             aria-placeholder="----"
|             aria-valuemax="275760"
|             aria-valuemin="1"
|             aria-valuenow="2014"
|             aria-valuetext="2014"
|             pseudo="-webkit-datetime-edit-year-field"
|             role="spinbutton"
|             shadow:pseudoId="-webkit-datetime-edit-year-field"
|             "2014"
|       <div>
|         aria-haspopup="menu"
|         id="picker"
|         pseudo="-webkit-calendar-picker-indicator"
|         role="button"
|         tabindex="0"
|         title="Show month picker"
|         shadow:pseudoId="-webkit-calendar-picker-indicator"
| <textarea>
|   id="textarea"
|   this.value="initial value"
|   <shadow:root>
|     <div>
|       id="placeholder"
|       pseudo="-internal-input-suggested"
|       style="display: block !important; user-select: none !important;"
|       shadow:pseudoId="-internal-input-suggested"
|       "suggested value"
|     <div>
|       "initial value"
| <select>
|   id="select"
|   <option>
|     "initial value"
|     <shadow:root>
|       <span>
|         aria-hidden="true"
|         pseudo="-internal-option-label-container"
|         shadow:pseudoId="-internal-option-label-container"
|         "initial value"
|       <slot>
|         pseudo="-internal-option-slot"
|         shadow:pseudoId="-internal-option-slot"
|   <option>
|     "inserted value"
|     <shadow:root>
|       <span>
|         aria-hidden="true"
|         pseudo="-internal-option-label-container"
|         shadow:pseudoId="-internal-option-label-container"
|         "inserted value"
|       <slot>
|         pseudo="-internal-option-slot"
|         shadow:pseudoId="-internal-option-slot"
|   <shadow:root>
|     <div>
|       aria-hidden="true"
|       pseudo="-internal-select-inner-element"
|       shadow:pseudoId="-internal-select-inner-element"
|       "initial value"
|     <slot>
|       pseudo="-internal-select-button-slot"
|       shadow:pseudoId="-internal-select-button-slot"
|     <div>
|       popover="auto"
|       pseudo="picker(select)"
|       shadow:pseudoId="picker(select)"
|       <slot>
|         id="select-options"
|     <div>
|       popover="manual"
|       pseudo="-internal-select-autofill-preview"
|       shadow:pseudoId="-internal-select-autofill-preview"
|       <div>
|         pseudo="-internal-select-autofill-preview-text"
|         shadow:pseudoId="-internal-select-autofill-preview-text"
| "input.value: initial value"
| "internals.suggestedValue(input): suggested value"
| "input.selectionStart: 0"
| "input.selectionEnd: 0"
| "month.value: "
| "internals.suggestedValue(month): 2014-01"
| "textarea.value: initial value"
| "internals.suggestedValue(textarea): suggested value"
| "select.value: initial value"
| "internals.suggestedValue(select): suggested value"
| "internals.suggestedValue(select): "